How to fix a Galaxy S9 that randomly reboots after installing an update

There has been a surge in #GalaxyS9 troubles recently so here’s another troubleshooting article. Like in previous posts, cases mentioned below are taken from users who contacted us directly. We hope you’ll find this post helpful for you.

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 network unlock a Galaxy S9 Plus

Hi. I ordered my Unlocked Samsung Galaxy S9 Plus from Samsung.com on April this year. Everything is fine, but I’m not able to make or receive a call since I bought until now. I switched 3 Carriers, brought my phone to Samsung care store to check it out, spending time with all my Carriers to get help with my issue. But my phone still gets the same issue. I just learned from Samsung technical support my phone was locked by US Cellular. I called Samsung, US Cellular and my current carrier T-mobile to unlock it, none of them want to do it. I saw on You tube showed how to unlock phone by paying UnlockRiver.com, so they can give the unlock numbers to unlock my phone. My question is, if I unlock my phone by the way on YouTube, can my phone able to call or receive a phone call? Thanks.

Solution: Carrier-branded devices like the one you have is originally built to work for a particular carrier.  Unlocking your phone does not right away means your phone will be able to use messaging and other network services of the current network you’re in. There are other factors to consider in order to make your device work with another network.

A network unlock code works by modifying some settings on your phone so its default network configuration are changed. This may or may not work. In general, a carrier will only unlock their device once all your obligations to them have been fulfilled. If you have outstanding balance with a carrier, they will demand that you settle it first before they can unlock your phone.

Even if you’ve already fulfilled all obligations and the phone has been network unlocked already, there are other reasons why your phone may not work when used in another network. There’s the factor of hardware incompatibility at play. Not all carriers operate in the same band frequency so phones built for them by Samsung also has specific radios. If the radio in your phone is not compatible with the current frequency of your carrier, your phone won’t be able to work even if it’s been network unlocked successfully. Try to do some research by knowing your device’s radio frequencies and comparing them to the frequency bands of your carrier in your area.

Normally, only carriers are allowed to unlock their devices but there are many third party shops both online and offline that can do the job. Be sure to dig deeper into the company that you want to get help from to see if they offer reputable service. Some of them can’t do anything if you have a CDMA device so don’t waste your money asking for unlock codes from these firms.

If you have a GSM device, unlocking is relatively easy and will most likely allow you to use your current carrier’s network services. Before you pay for an unlock code, be sure to contact your network operator to ask if your phone is compatible. Remember, getting an unlock code will not magically remove restrictions on your phone or make it compatible. Working closely with your carrier is necessary so you get accurate, first hand information.

Problem #2: How to fix a Galaxy S9 that randomly reboots after installing an update

I just got a Samsung s9 and when I connected to wifi it updated the software. Now it’s turning off and on and when i try to do a hard reset it gives me this message “security error: this phone has been flashed with unauthorized software & is locked. Call your mobile operator for additional support. Please note that repair/ return for this issue may have additional cost. ” the phone was bnib this afternoon, is there anything I can do?

Solution: Is this a brandnew Galaxy S9? If it is, don’t waste your time by fixing the issue on your own. We suggest that you demand for a replacement to save you from hassles.

If the device is pre-owned or previously used, we can’t think of a reason why an OTA (over-the-air) update will lead to this situation. We assume of course that you update the device normally and not via Odin. If the error occured after an OTA update from your carrier, make sure to contact them so they can create a ticket about the issue.

In some rare cases, normal updates may lead to boot loop or random shut downs. If you did not tamper with the software in any way and the only different thing done was to install an OTA update, factory reset may help. Try booting the device to Recovery Mode and factory reset it. Here’s how:

  1. Turn off the device. This is important. If you can’t turn it off, you’ll never be able to boot to Recovery Mode. If you are not able to shut the device off regularly via the Power button, wait until the phone’s battery is drained. Then, charge the phone for 30 minutes before booting to Recovery Mode.
  2. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
  3. When the green Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
  4. Press the Volume down key several times to highlight ‘wipe data / factory reset’.
  5. Press Power button to select.
  6. Press the Volume down key until ‘Yes — delete all user data’ is highlighted.
  7. Press Power button to select and start the master reset.
  8. When the master reset is complete, ‘Reboot system now’ is highlighted.
  9. Press the Power key to restart the device.

If factory reset will help, work with your mobile operator to figure out what went wrong with their new firmware update.

Problem #3: Galaxy S9 can’t make a call or call keeps dropping

I have recently purchased a dual sim from Kogan Australia and moved from Virgin mobile (which no longer operates in Australia) to optus (Virgin used the optus network so I thought there would be no issues). I previously had a samsung s7, great phone. I am in a capital city however now when I am in my car either through bluetooth or when the car is stopped I cannot make a call or it drops out, hangs like its trying to connect and over 5  km, will ring and then nothing or doesn’t connect at all. It’ the same when I receive a call I go to answer and it just hangs and doesn’t connect. Also I use the Waze app (Navigation) which also worked great on the Samsung S7, it keeps dropping out in the location etc. I have called Samsung 3 times and Optus twice, they say see the supplier Kogan?

Solution: The reason why Samsung or your carrier refers you to the retailer is to get a replacement, which is a more efficient option to resolve the issue than do some basic, unguaranteed troubleshooting. There’s no direct way to know why your S9 works this way so Samsung or your carrier wants to save your time and effort by getting the device replaced right away. Before you do that though, we suggest that you try two simple troubleshooting — reset network settings and factory reset.

How to reset your S9 network settings:

  1. From the Home screen, swipe up on an empty spot to open the Apps tray.
  2. Tap General Management > Reset settings.
  3. Tap Reset network settings.
  4. If you have set up a PIN, enter it.
  5. Tap Reset settings. Once complete a confirmation window will appear.

How to factory reset your Galaxy S9

Refer to the steps above.

If both troubleshooting steps won’t make any difference, go ahead and get the phone replaced.

Problem #4: Galaxy S9 won’t detect SD card

My Galaxy S9 suddenly will not recognize my SD card at all. It did this once a few months ago when it got too hot and all I did was turn off the phone to cool it down for about an hour then turned it back on and my card was again recognized. This time out of the blue it happened when my phone had not been used in a few hours and was recently charged. It is in a case so I am pretty sure no dirt got in where the card is located. Please help! Not sure of Android version.

Solution: There are two general reasons for this problem — either it’s an issue with your SD card, or there’s a bug in your phone. To know which one is easy. Here’s what you need to do:

  1. Reformat your SD card using your S9,
  2. Restart your S9 and check for the problem.
  3. If everything works normally, then you’re probably good to go.
  4. If your S9 can’t read the SD card after it’s been reformatted, get another SD card. This will help you tell if the issue is phone-related or not.
  5. If your S9 detects the second SD card and can use it normally, then the first SD card must be defective. Otherwise, you should have a phone issue.
  6. If you think it’s a phone issue, do a factory reset and see what happens. Factory reset should clear the software of bugs.



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