One of the things I like about Android is it’s an open system. I run Cyanogenmod on all my devices – phones & tablets. This eliminates manufacturer bloat, carrier bloat, gives me a clean pure Android experience with higher performance and better battery life, one-click rooting, full control over the device, and enables me to keep using them long after the manufacturer abandoned them to the planned obsolescence of “no more updates”.
I use my Galaxy Tab 3 8.0 as an electronic flight bag when flying. It’s an old tablet but it’s the perfect size for my kneeboard, has good battery life with enough performance to run my aviation software with GPS moving maps and other features. Recently, a developer on XDA-Developers ported CM13 to this device – and also ported TWRP too! I couldn’t resist. Worst case, if it was buggy, I could always revert to the last OEM supported version (Android 4.4).
Long story short, it worked great. It’s an unofficial build but works as well as any OEM build. And CM13 has nice extras like better battery life, better app permissions control and more customizability. Regarding the last point, it has Themes. When I’m in the mood for a dark theme (which also saves battery live on AMOLED screens), my favorites are Ash and Blacked Out.
Today I decided to try a new dark theme: Deep Darkness. When I turned it on it killed my tablet. That is, the home screen was still there but a system model dialog “System UI has stopped, (R)eport OK”. popped up every 5 seconds, and the tablet was unusable. I thought I would have to boot to recovery and wipe the tablet, but fixed it without that drastic step.
In summary, use the command prompt to wipe the internal Themes directories and remove the offending Theme. Here’s what I did:
First, get the full package name of the theme you installed. In my case, it was com.blissroms.moelle.ddoverhauled-1. Google is your friend here.
Now USB connect the tablet to a computer with ADB. Fortunately, I had the tablet defaulting to debugging mode and my computer was already authorized – because without a functioning system UI I wouldn’t have been able to switch it. Open a command prompt on your computer and use ADB:
adb devices
Checks to ensure it’s recognized. If not, you’re out of luck because without a working UI on your device, you won’t be able to turn dev mode on or authorize the computer it’s connected to. However, if you have a recovery like TWRP that has a file manager, you can boot to recovery and use that. If adb works, you have 2 ways to fix it.
adb shell
This worked, giving me a command prompt on the device. Even though the UI was dead, the OS was still running. Now you must find the app. It could be in /system/app, or /data/app. If you installed it recently, try ll -tr to get a time-sorted listing, newest last.
Now remove this app. First, try the clean way from your computer’s command line (not from the ADB shell on the device):
adb uninstall com.blissroms.moelle.ddoverhauled-1
But this didn’t work for me, said “Failure [DELETE_FAILED_INTERNAL_ERROR]”. Most likely because the Theme was being used. You don’t need to uninstall – you can simply nuke the app & its directory. You can do this from adb shell with rm, or you can boot to recovery, use the TWRP file manager feature. You will first have to tell TWRP to mount the system and data partitions. And you cannot mount them read-only, because you’ll be deleting files from them. From your ADB shell:
rm -fr /data/app/com.blissroms.moelle.ddoverrhauled-1
Next, remove the system themes directory – just nuke it. When it’s not there, CM13 will deal with it on boot, reverting to the stock CM13 theme. If you have to make the /system partition writeable, try this as root:
mount -o rw,remount /system
Again, you can do this from TWRP recovery or from your ADB shell:
rm -fr /data/system/theme
Next, reboot the device and you’re fixed, back to the system default theme.