How to fix your HTC U12/U12 Plus that suddenly went dead and won't power on [Troubleshooting Guide]

Unexpected shutdown and reboots in mobile devices can be attributed to a system issue, if not hardware damage. This can also occur among other symptoms of memory problems like when the device is running low on storage. New devices can also give into the same issue when certain apps are misbehaving or when a bad update caused major data corruption.

In worst cases, this can be a direct indication of hardware damage either physical or liquid damage. Before rushing to a service center, there are some workarounds you can try to fix the problem on your end and get your device back up and running. The following solutions I’ve demonstrate are particularly applied to an HTC U12/U12 smartphone that’s unexpectedly shutting down and refuses to power on. Read on for more detailed solutions.

Before we move on to our troubleshooting, if you are looking for a solution to a different issue, make sure you drop by our troubleshooting page as we’ve already addressed some of the most common problems reported by our readers. Find issues that are similar with yours and use the solutions we suggested. If you still need our help after that, then feel free to contact us by filling up our Android issues questionnaire.

First solution: Charge your phone.

The phone may have run out of power completely and so it suddenly shuts down as other phone does when the battery is emptied. To get it back up and running, it therefore needs to charge up. That said, connect your phone to its charger and then allow it to charge until it gets full.

If your phone doesn’t charge, check and ensure that you’re using the original/OEM charger and that the charger is working. You can also switch between power outlets to make sure the power source is working too. It may take longer for the phone to show charging indications especially if the battery was totally drained. Just wait until it accumulates enough power and then charge up to a hundred percent.

Second solution: Force restart while charging.

Forcing the phone to reboot while charging can also help clear any errant apps that might have caused the phone to shutdown unexpectedly. A force restart is a simulated battery removal procedure carried out on unresponsive devices. It forcibly quits running apps and dumps corrupted data and cache from the internal memory. In this case, force restart your HTC U12/U12 Plus while it’s connected to the charger.

To force restart your HTC U12/U12 Plus, press and hold the Power button for at least 10 seconds and then release when the phone reboots.

If the phone managed to boot up, then let it charge while it’s on. Otherwise, give it more time to charge until the battery is full and then that’s the time you can troubleshoot further.

Third solution: Wipe cache partition.

If you’ve managed to turn your phone back on, you can further troubleshoot to eliminate the possible triggers and prevent the device from acting up again. As the next possible solution, try wiping cache partition on your phone. This is highly recommended after installing a major system update on your device. Doing so will clear any temporary data that were corrupted from the update and eventually triggered the system to misbehave and become unstable. Here’s how to wipe cache partition your HTC U12/U12 Plus:

With the phone powered off, press and hold the Volume Down button while turning the phone on.
Continue to hold the Volume Down button until the bootloader screen is displayed.
Press the Volume Down button until Recovery is selected.
Press the Power button to confirm selection. The phone will then seem to reboot and the screen will turn black for 15 to 30 seconds.
Wait until the recovery screen is displayed then continue with the next steps.
Hold the Volume Up button and then press and release the Power button.
Press the Volume Down button repeatedly until Wipe Cache Partition option is highlighted.
Then press the Power button to confirm selection.
Press the Volume Up button repeatedly after the process completes.
Press the Power button to select Reboot system option.

Your phone will then execute its normal booting sequence.

Fourth solution: Reset your phone and restore factory defaults via Android recovery mode.

If the previous method failed, then try to enter recovery mode again and this time execute a master reset to wipe and restore factory settings and default configurations on your device. Here’s how:

With the phone powered off, press and hold the Volume Down button while turning the phone on.
Continue to hold the Volume Down button until the bootloader screen is displayed.
Press the Volume Down button until Recovery is selected.
Press the Power button to confirm selection. The phone will then seem to reboot and the screen will turn black for 15 to 30 seconds.
Wait until the recovery screen is displayed then continue with the next steps.
Hold the Volume Up button and then press and release the Power button.
Press the Volume Down button repeatedly until Wipe Data/Factory Reset option is highlighted.
Then press the Power button to confirm selection.
Press the Volume Up button repeatedly after the process completes.
Press the Power button to select Reboot system now option.

Allow your device to finish booting up and then see if the problem is fixed.

Fifth solution: Wipe and restore your HTC U12/U12 Plus in Android recovery mode.

Continue to troubleshoot your phone in recovery mode if the prior method failed. This time try performing a factory data reset and then wipe cache partition respectively. This should clear any system errors that might have caused the system to crash and shut down. Here’s how it’s done:

With your device powered off, press and hold both the Volume Down and Power buttons simultaneously for a while.
Release the Power button but keep holding the Volume Down button when the HTC logo appears.
Release the Volume Down button when you see Download Mode.
Then, press the Volume Down button to scroll down and select Reboot to Bootloader option.
Press the Power button to confirm selection.
Press the Volume button to highlight/select Boot to Recovery Mode.
When the warning image shows up, press the Volume Up and the Power buttons once. The Android Recovery menu options will then show up.
Press the Volume button to scroll to and highlight any further options and then the Power button to confirm selection.
Press the Volume Down button repeatedly until Wipe Data/Factory Reset option is highlighted then press the Power button to confirm.
Press the Volume Down button again to highlight Wipe Cache Partition, then press Power to confirm.
To reboot your phone, select the option to Reboot system now and then press the Power button to confirm

Let your phone system reboot.

Other options

Service can be considered among the next option if none of the above methods is able to solve the problem and your HTC U12/U12 Plus repeatedly shuts down by itself and have trouble turning back on. The emerging symptom could also denote hardware damage on your the phone from a previous drop or exposure to liquid. In this case, physical repair would be necessary. You can take your phone to the nearest HTC service center in your area for that matter. Otherwise, contact your device carrier for further recommendations and support.

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How to fix your HTC U12/U12 Plus that suddenly went dead and won’t power on [Troubleshooting Guide]