Hmmmm. My phone was in safe mode and so to get it out of this mode I tried to restart my phone. This caused it to return to the custom OS warning screen. I have done the same trick again and so my phone is on and working, but in safe mode. I'm too scared to restart it again now. Is there another way to get it out of safe mode? Why is this mode even enabled?
(I have managed to find out the firmware. It is I9505XXUBMEA if this means anything to you?)