Please, someone, please help, I have tried hard reboot, holding up button, etc. I have heard that afc2add doesn't work in iOS 7.1.2, but I didn't know that when installing. PLEASE HELP! Thank you.
You need to hold down the power button and the 'normal' one together for several seconds (10') to enter in DFU mode. Then, connected to iTunes, install the latest iOS 7.1.2 again. Set it up as a new phone, jailbreak again with the latest Pangu version, and restore from backup. Done!