+1 for proximity sensor problems. We don't have your exact machine but I bet the changer is the same.

We had the "not safe" error too, it was the return sensor not telling the control the carriage was back. You can get to the params screen and see the switch states, cycle it a few times and it should show up. Both have to work - one forward, one back, and they switch states depending on position. If one fails it freaks out. Plus there's one for the geneva position, and one for tool 1 position / home if I remember right. Ours had the "back" carriage switch not working because the tool changer eccentric arm worked loose and was not in position in front of the prox. switch. Check that arm (the one with the bearing that runs the carousel in and out, driven by the motor) maybe it's worked loose like ours did.