Just picked up a Stellar Wars in non-working condition, the cabinet and play field were beautiful though. I am pretty new to repair and have been trying to read as many guides as possible but I think I may need an assist here.

This is what I have done so far:
- Referred to the schematics and made sure all of the connections were correct.
- Cleaned each of the connections using contact cleaner.
- Checked all of the fuses, one fuse was blown it was the fuse for the solenoids
- Noticed that the cable used to ground the speaker was disconnected, and reconnected.

I tried both auto-up, and manual down mode. The machine lights up, but is unresponsive and none of the displays illuminate.
When the machine is turned off the speaker does output a noise, like something the game would do during play. I opened the head of the machine and noticed that both the lights on the cpu board were illuminated, according to the manual that indicates a board failure. I tried to self-test the board using the diagnostic button on the board. I also tried entering master commands, nothing appears to be working though.

A few things have confused me so far:
- Why do the schematics refer to a system 6 board but a system 4 is installed?
- Why do I only have 3 chips when the diagram refers to at least four?
- Why is the master display not displaying anything?

Lastly, what do you think I should try next? I would love to hear your thoughts!
Thanks in advance to anyone who takes the time to reply to this thread!

P.S. I'm still very new to this and I apologize for asking any stupid questions, I just really want to learn how to fix this.

Out of curiosity, why is contact cleaner a bad idea?

I will check the voltages and report back after work tomorrow, could you link any guides for repairing boards. I don't mind if it's a pretty involved process, I plan on fixing many more in the future... but I need to take my time and learn first.

Thanks for the help so far guys, I've been pretty busy so I apologize for the delay with testing and uploading photos. I will make sure I get to it tonight though.