I experienced my first error after jailbreak my new ipad 3. I got screen stuck after I installed mountainlioncenter and restart springboard. The springboard got stuck for few minutes without response. My new iPad 3 is still running and detectable by iTunes but not able to restart the springboard. At the end, I decided to do hard reset. Hard reset is force shutdown and restart your IOS devices without saving any data at that moment. You will not lost any apps or data that already saved before hard reset.
1. Easy. You need the power button and home button physically.
2. Press and hold Power + Home buttons until the screen become dark and the Apple logo appear at the middle of the screen. It takes about 10 secs.
3. Once you see the Apple logo, wait the device to reboot. It may takes up to few minutes.
4. You are done and your devices should work as usual.