How to reboot a frozen Android device?
Different Android devices may have different force-reboot methods, so you should refer to your device’s documentation. To reboot frozen device you should usually press and hold the Power button + Volume Down button (or Volume Up button - it depends on device) for at least 7~10 seconds and stop holding those buttons once it’s started the reboot process. You could try to press and hold just the Power button itself for at least 30~45 seconds.