Galaxy S7 turns off when disconnected from the charger, won’t stay on, screen stays black

Black screen and No Power issues are some of the most common problems for Android devices so today’s troubleshooting article addresses this issue on the #GalaxyS7. There are three S7 users that we would like to help in this post so hopefully, they’ll find this material in a timely manner.

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: Galaxy S7 screen is black, won’t power back on

S7 edge, SM-G935FD. Phone showed 35% battery and then shut down. I have tried every possible combination of buttons to start it in any mode but nothing works. The screen will not turn on, no vibration or screen logo. No LED  light. plug the phone in to charge, no LED light, no screen battery logo. Phone gets hot after its plugged in while. Phone worked perfectly until this happened. — Xavier

Solution: Hi Xavier. Technically, an end user of a Samsung device has very limited troubleshooting options when it comes to an issue like this. In almost all similar cases, the problem is either due to a failing battery or a dead motherboard so hardware diagnostics is necessary. Before you send your phone in, we suggest that you do the things below:

Use another charging cable and adapter

One of the possible reasons why your phone does not power on at this time may be a low battery power situation. In some cases, the main reason why a battery appears dead is due to the fact that the phone has lost its ability to charge because the charging cable or adapter is damaged. To see if this is the case, make sure that you check the USB cable and adapter for obvious signs of damage. A bad USB cable may not provide enough power to the battery during charging. Even if the cable may not have detectable damage and looks perfect outside, it may still be defective inside so make sure to try another set of charging cable and adapter to replace the current set. Make sure to use a known working and compatible USB cable and adapter.

Check the charging port

Your phone’s charging port is exposed to elements so there may be something inside that can interfere with its function. Sometimes, pocket lint, dust, sand, or any foreign debris can reside in the port and prevent the charging cable from making good contact with the pins inside. To inspect the port, try to use a magnifier or something similar to see the inside more clearly. If you think the port may be dirty or has some lodged particles that should not be there, try to clean it using a can of compressed air. Avoid sticking anything inside to prevent damaging anything.

Check the outlet

If you tend to charge in your favorite outlet at home, consider using another outlet to charge your phone to eliminate the possibility of a bad outlet issue. Alternatively, you can try to plug in another device to your favorite outlet to see if its working or not.

Send the phone in

Should nothing of these tips above won’t help, the most likely reason for the problem is the phone itself. It may be a malfunctioning/dead battery or any failure in the logic board so you’ll need to let a trained professional check the phone for you. At this time, we doubt that your phone is still within the standard one-year warranty but we still highly recommend that you let Samsung fix the phone for you. This is to guarantee that you’ll get a fixed device afterwards.

Problem 2: Galaxy S7 turns off when disconnected from the charger, won’t stay on

Hi. My S7 only stays on when I have it hooked up to the charger, and if it ain’t the adaptive fast charging then it won’t power on. It just keeps on restarting at the Samsung logo, and when I unplug it from the charger it instantly turns off till I plug it back in, even with the battery fully charged, as soon as I unplug it it dies and I plug it in and the battery meter says 0.

i rooted my phone and multiple custom ROMs in it, and then accidently activated the samsung FRP. then I decided to put the stock firmware back in it, but the drk-eng binary thing happened, so with the frp lock on it prevented me from flashing anything to fix it, then I flashed these combination files like 2 months not turning it on and it booted up and that’s when my battery failure happened. Is there anything I can do to fix this problem? I heard that flashing the ROM too many times can mess the battery up. Is this a common issue or can it be fixed? Thank you. — Ricky Brown

Solution: Hi Ricky. Flashing, as long it’s done properly, won’t result to any serious problems. If you encounter problems with your device now, that means that along the way, flashing may have messed something up. It’s possible that you may have corrupted some system files critical to your phone’s power management system, including the ones that help the battery work properly. Flashing won’t affect the battery in a physical sense but since it uses a code (firmware) to work with Android, it’s possible that there may be a code-related issue that causes it to work erratically. There’s no way to know check this though so we can’t confirm if it’s the case or not.

There are two things that you can do that might help fix the problem. The first one is to recalibrate Android and the battery. The second is to reflash the bootloader.

To do the first suggestion, follow these steps:

  1. Drain the battery completely. This means using your device until it powers down by its own and the battery level reads 0%.
  2. Charge the phone until it reaches 100%. Be sure to use original charging equipment for your device and let it charge up completely. Do not unplug your device for at least two more hours and also, don’t use it while charging.
  3. After the elapsed time, unplug your device.
  4. Restart the phone one more time.
  5. Use your phone until it completely runs out of power again.
  6. Repeat steps 1-5.

Should Android and battery recalibration won’t work, consider reflashing the bootloader back to stock. If you’ve already tried this before you contacted us, simply ignore this suggestion. In some situations, it’s also recommended that you reflash the firmware back to stock so be sure to do that should flashing the bootloader won’t help.

Flashing the bootloader of any Samsung device is generally the same. However, we suggest that you consult other guides as well so you’ll have an accurate set of steps to follow before eventually doing anything drastic. Below are the steps on how to reflash a bootloader of a Galaxy device:

  1. Look for the correct firmware for your phone model and download it. Make sure that you select the right one. It should be the same exact firmware that ran previously on your device. We assume that you list down the firmware version somewhere. If you did not take note of it before, there’s a chance that you may pick the wrong one. As you may know now, using an incorrect firmware can cause complications so good luck with that.
  2. Let’s now say that you have identified the correct firmware. You then want to download it to your computer. The firmware file should have a bunch of files in it like AP_, BL_, CSC_, etc.
  3. Look for the file that starts with a label BL; this should be the corresponding bootloader file for this firmware. Once you’ve identified the bootloader file, copy it to your computer’s desktop or to any other folder that you can easily access.
  4. Proceed with the rest of the flashing procedure using the Odin program.
  5. In Odin, click on the BL tab and make sure to use the bootloader file you’ve identified earlier.
  6. Now, make sure that the “Device Added” status and its “ID:COM box” has turned blue before hitting the START button. This will initiate the flashing of your phone’s bootloader.
  7. Restart the phone once the procedure is finished.

Problem 3: What to do if your Galaxy S7 won’t power back on

Hello there. I do hope you can help me. I have a Samsung Galaxy S7. I noticed there was as update available for it which I downloaded. This took about 30 mins. The phone seemed to have some trouble restarting after the update. But eventually I did get it to start. I then plugged it in to recharge it fully and I turned it off (it was about 50% charged at the time). However when I went to turn it on it on again it simply would not turn on at all. Needless to say I have tried all the variations of pressing volume keys/ power keys and home keys suggested by your site. Anything that you can suggest to save it would be most appreciated. — Francis Marshall

Solution: Hi Francis. Your issue is similar to Xavier above so kindly refer to our suggestions for him on what to do. Hopefully you’ll be able to fix it on your end without needing to send the device to Samsung for repair.


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