If a reboot doesn't resolve, that machine may need to have it's firmware reloaded or some hardware replaced.
I found an article for power cycling on and off. If you are still having issues after trying these steps, I suggest that you call into our support department for assistance @ 1-800-821-2797.
I searched the online Support and found this article for power cycling that may help you.
I'm hoping someone could help me out on this one...
Xerox Workcentre 7225 is displaying the red letter "P" code on its controller board power keeps cycling, display never turns on. Hard drives spinning, green check lights on controller are on as well as the ethernet link / activity.
Controller cycles through self test up until "P" then resets after one second and repeats forever.
Any input on this code would help!