When encountering the servo error there are a few things you can try ( though if the power supply failing is the problem this won't work.)
Turn off printer and base. Carefully clean and lube the rails.
Clean the screw drive from the very front all the way to the very back, and then lube generously especially where it connects at the front and at the back and printer. Turn base on and wait 1 minute, then turn printer on and wait one minute. Press the green button and see if it will move forward /back without servo error.
It is possible you might need to manually turn the screw drive to move the printer home- then turn on in sequence, you can try it again.
If this does not work you can also loosen the rail screws and try to run the printer forward and back with the rails loose. If this has success, then very gently tightening them back, run it forward and back and see if the servo error remains gone- if not loosen more again.