My Back to the Future is sick.
I don't know what happened, but (making a long story short) something caused the PIA chip on my MPU to fry. That was repaired, and now the game boots up and plays. However, there are no playfield lights, sound or left sling coil, just GI lighting. Obviously something spiked the game and took out a bunch of stuff. BTW, I have a new Rottendog power supply now.