How to fix Galaxy S8 incomplete connection error when charging, won’t turn on issue

Today’s #GalaxyS8 troubleshooting article addresses two power-related issues — incomplete connection error when charging and won’t turn on (No Power). The first one (incomplete connection error when charging) started happening sporadically since last year while the second one is a perennial trouble across all types of smartphones. In this post, we address both of them to enlighten users on what directions to take when faced with them. In cases where the main reason is bad software, users will be able to usually these issues on their end. However, for cases with more severe hardware causes, repair or replacement may be necessary. We hope that we’ll be able to help our ever-growing Android community with this post.

If you are looking for solutions to your own #Android issue, you can contact us by using the link provided at the bottom of this page.

When describing your issue, please be as detailed as possible so we can easily pinpoint a relevant solution. If you can, kindly include the exact error messages you are getting to give us an idea where to start. If you have already tried some troubleshooting steps before emailing us, make sure to mention them so we can skip them in our answers.

Problem 1: How to fix Galaxy S8 incomplete connection error when charging

Everytime I try to charge my phone it says it’s incomplete connection. I’ve tried charging it while completely powered off but it will charge incredibly slowly. Like 14% to 55% takes 8 hours. I’m still using my original charging block and cable. I’ve tried charging it using a computer as a power source but that doesn’t help either. I’ve only had the phone since June 2017 so about 7 months. I’ve also checked both sides of the cable and the port and there doesn’t seem to be any debris or dirt that could get in the way. I feel as if I’ve tried everything. — Maddy

Solution: Hi Maddy. Given the fact that there’s a long list of Samsung Galaxy S8 users who reported about this issue starting last year, we want to think that this might be an accessory issue rather than a phone one. We’ve been monitoring this issue for months now but you’re the first one to specifically report S8 incomplete connection error when charging. A lot S8 charging  issues we received for the past few weeks are about the missing fast charging functionality.

Since Samsung has not released any official acknowledgement of S8 incomplete connection error at this time, we’re actually left with piecemeal or anecdotal accounts from other users on how to fix the problem. Below are the possible solutions that might help you.

Return all software settings back to their defaults

As mentioned above, we don’t believe that the issue lies with the phone. Still, we want to ensure that there’s no software bug causing it. So, to eliminate that possibility, make sure that you begin your troubleshooting by reverting all settings to their factory state. After you’ve factory reset your S8, you can then start to narrow down the possible issues with the accessories.

If you haven’t tried doing a factory reset in your S8 before, follow these steps:

  1. From the Home screen, swipe up on an empty spot to open the Apps tray.
  2. Tap Settings > Cloud and accounts.
  3. Tap Backup and restore.
  4. If desired, tap Back up my data to move the slider to ON or OFF.
  5. If desired, tap Restore to move the slider to ON or OFF.
  6. Tap the back button to the Settings menu and tap General Management > Reset > Factory data reset.
  7. Tap Reset device.
  8. If you have screen lock turned on, enter your credentials.
  9. Tap Continue.
  10. Tap Delete all.

Before doing a factory reset, be sure to back your important files such as photos, videos, etc.

Observe how your phone charges when there are no third party apps

Now that your phone has been wiped clean, it’s time to determine how it charges. One important note to remember is never to install any app yet during this time. If you’ll install your apps right away after a factory reset, there’s no way for you to know if any one of them is to blame. Just leave your phone running with defaults settings. Use the phone until the battery is drained, then observe how it charges.

If your S8 will charge properly and the incomplete connection error won’t show, then there might be an issue with one of your apps, or with the operating system. To see if it’s an app issue, make sure to install apps one by one. After every app installation, be sure to try charging the phone. Do the same cycle for every app until you identify the culprit.

If your S8 will continue to show the incomplete connection error even when there are no third party apps, proceed to the rest of the troubleshooting below.

Clean the tips of the charging cable

One S8 owner was able to successfully fix the issue by cleaning the ends of the charging cable so be sure to do it as well. Each tip of the charging cable is exposed so if there’s dirt positioned in the right spot, it may cause an incomplete connection to either the adapter or the charging port in your phone.

Move the cable when charging

This one is a common trick for those with either a bad/damaged charging cable or charging port. Still, this is a proven workaround by one of S8 users who reported the trouble so there’s really nothing much that you’ll lose if you try it. When charging, try to move the cable sideways and see if that will fix the problem.

Use another charging cable or adapter

For any charging issue for any smartphone, it’s always logical to try a different set of charging cable or adapter to narrow down the possible causes. Some S8 users were able to fix their incomplete connection error issue by exchanging the charging cord. If you have a different charging cable to use, be sure to try it with your S8.

Use can of compressed air to clean port

Your Galaxy S8 is supposed to be water and dust resistant so cleaning the charging port for possible dirt or lint blocking the pins or charging cable may appear illogical. Still we recommend that you do it in order to ensure that this part of your phone is working as expected. Do not stick anything into the port to avoid damaging any of the connectors. Instead, try using a can of compressed air to remove possible dirt or debris.

Contact Samsung for support

Should all the suggestions above won’t help in fixing your problem, then you need to let Samsung know about it. At this time, we don’t have any data if this is fixable by repair or if you’ll  end up with a unit replacement.

Problem 2: Galaxy S8 completely unresponsive and won’t power back on

My phone has alerted me to update my phone but haven’t updated it for a week because I need to clear up some space or memory from my phone before it can update. But I haven’t had a chance to do so the past week. So it just keeps reminding me to install update and I just keep hitting install later. I was on my phone last night with low battery and I put it to charge. When I woke up in the morning it was a black screen with blue pulsating light and didn’t turn on. I have been trying everything. Soft reset (hold power button and volume down) and the hard reset ( holding power, home and volume up button) but nothing comes up on the screen and those two didn’t work. I removed the SIM card and when I inserted it back in, it was still a black screen but NO blue light anymore. My phone is charged. Now I have just a black screen NO lights blinking. Help me. Could it be the battery? — Melissa

Solution: Hi Melissa. Assuming you did not

  • accidentally drop,
  • physically impact,
  • or expose your phone to elements (water, too much heat or cold)

before it stopped responding, then the possible causes for the issue should include the following:

  • software glitch,
  • bad battery,
  • bad charging cable and/or adapter (so phone no longer charges properly or at all), or
  • unknown hardware error.

The first troubleshooting step that you need to do in this case is to try using another charging cable and adapter. This will help narrow down the issue by eliminating the possibility of your phone not charging.

Once you’ve found another another known working charging cable and adapter, make sure to charge the phone for at least an hour. This will be more than enough to charge the battery to power the phone back on (presuming that the battery is not the issue of course). If your phone appears to charge and starts showing some signs of life like LED light lighting app, continue charging the phone for 1 hour. If the screen remains black afterwards, try to see if you can boot the device up to alternate boot modes. If you’ll be able to do it, then there’s more likely an operating system issue. Doing so will also help you determine if there’s a problem with the screen or not. Generally, if the issue lies on the screen only, the phone will show signs of life although the screen will be black. In this case, you should be able to ring your phone.

For reference, here are the steps on how to boot your S8 to alternate modes:

How to restart an S8 to Recovery mode

  1. Charge the phone.
  2. Press and then hold Bixby and Volume Up keys, then press and hold the Power key.
  3. When the Samsung Galaxy logo shows on the screen, release the Power key but continue holding the Bixby and Volume Up keys.
  4. When the Android logo shows, you may release both keys and leave the phone be for about 30 to 60 seconds.
  5. In Recovery Mode, you can either wipe the cache partition or do a factory reset when in this mode.

If your S8 won’t load Android when in normal boot mode, be sure to do a factory reset.

How to restart an S8 to Download Mode

  1. Charge the phone.
  2. Press and then hold the Bixby and Volume Down keys, then press and hold the Power key.
  3. When the Samsung Galaxy logo shows on the screen, release the Power key but continue holding the Bixby and Volume Down key.
  4. Wait until the Download screen appears.
  5. If you can boot the phone in download mode but not in other modes, that means that your only way out may be to flash a stock or custom firmware.
  6. Use Google to look for a guide on how to do it.

If the phone is still totally unresponsive — no lights, no sound, no vibrations, screen not working — then you’re only course of action is to send it in. in this situation, a thorough hardware diagnostics is necessary to identify the failing component. It can be the battery, a power management IC, or some other motherboard components.

If your S8 is covered by a warranty, make sure to contact Samsung.

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Harvey Hisona

Harvey is keen with mobile technology and loves writing about all things mobile. He is passionate in helping technology-challenged people by finding resolution to their issues. Contact me at Email

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