Changed nothing on a Metallica Premium I help maintain on a route. Got the call that it wouldn't coin up (coins or bills). The coin pulses froze the animations on the playfield, then a pop and an immediate reset, but it looked like a "soft" reboot, not a full one. Checked connectors, wiggled wires in and around the coin door and nothing. Decided it had to be some sort of corruption of the settings. Did a factory reset and it fixed the issue completely. Like it never even happened.
Putting this out there so if someone else runs across the issue on Metallica or another Stern, the solution will be here.