Once on a flight they rebooted the airplane. Odd experience. Unfortunately it did not help ;-)
Ha, I also had that happening once, it was the best that Boeing/Seattle in an emergency call could come up with, a cold reboot. Fortunately we were still on the ground

After switching off all electrical power, they hoped that the faulty 2nd autopilot relais would initialize okay, and it did.
Cheers,
Bart