Don't know if you got it fixed, but I had to work on one of these with the very same problem. Either the main power controller was bad or the ink loader was bad. I replaced them and the printhead. There was CYAN ink all inside the printer around the heat block which holds the printhead. The biggest clue to the problem was nothing in the waste tray.
91,720 Printhead Tilt Fault
A Printhead Tilt error has occurred. The following troubleshooting procedure applies to this
I suggest you look for ink spills or/and obstructions around the printhead.
Please remember to select "Accept as Solution" for posts that helped you solve the issue.
We have a Xerox ColorQube 8700 with less than 1,000 pages printed on it, however it is no longer under warranty as we just don't use it that often. Yesterday I was running the Light Stipes Test to try and clear up some issues with the Cyan color not printing quite right and the machine rebooted on it's own and since then it won't print anything.
The message we see on the display is: Copying and Printing not available. System Fault. Error Code: 091-720
I was hoping that someone could give me an idea of what the error code means so that I can evaluate how I want to proceed.