cyanogenmod - How can I reset my developer options, or otherwise boot my Galaxy S2 on CM10.1 again?

I have a Samsung Galaxy S2 and the ROM I'm using is CM10.1. I was messing with the Developer Options and I saw an option called "Simulate Secondary Display". I clicked that and selected 720 then it froze. I forced rebooted it and it stopped at the end of the boot animation and get stuck there.

Any ideas how to fix this, preferably without flashing a new ROM?

Answer

In this situation you have two options, which I'd try in the given order:

Safe Mode

Boot into Safe Mode (details for what Safe Mode is and how to boot your device into Safe Mode can be found in the article How to Boot Android 4.1+ into Safe Mode:

• Method 1:
  
  
  
  
  1. hold down Power button until the power-menu pops up
  
  
  2. press and hold the "restart" option
  
  
  3. in the dialog box, select "Safe Mode" and hit "OK"
  
  
  
  


• Method 2:
  
  
  
  1. Reboot your device
  
  
  2. hold the Vol+ and Vol- buttons at the same time to enter Safe Mode.
  
  
  
  
  

A "Safe Mode" watermark in the lower left corner tells you you've been successful. Obviously, you'd have to chose Method 2 as your device won't power up normally.

Now, while in Safe Mode, change the "Developer options" back to normal. Then do a normal reboot to leave Safe Mode.

Hint: If your device sticks in Safe Mode, power down and remove the battery for a few minutes. Then re-insert the battery, and the device should boot up normally.

Factory Reset

As a last resort, you can do a factory reset. Be aware that this will delete all your data, plus the apps you've installed yourself (i.e. the pre-installed apps won't be touched; your SDcard should also remain untouched). As your device still is unable to boot up normally, you can reset it via the recovery menu. Check your device's manual for how to boot into recovery; on many devices, this is done by holding the Vol+ and Power buttons pressed simultaneously until the device booted up to recovery. Other devices may use different combinations; so either try a few, try Google search, or search our site for it. Of course you can ask it in a separate question if you're still out of look ;)