Quoted from MrBellMan:when the game is powered on, the playfield and backbox lights come on, but that’s it. The score motor does not move nor does anything else. I have tried to make sure no tilt/slam switches were stuck closed, the fuses are good and the fuse holders have continuity. I tried adding credits, pushing the start button, but nothing.
If the Start relay (S) doesn't activate when you push the Replay button,
Inspect and diagnose this circuit with Alligator clip jumper wires
https://pinside.com/pinball/forum/topic/gottlieb-big-shot-repair#post-6305153
http://www.planetimming.com/Pinball/troubleshooting/EM%20Troubleshooting.pdf
http://www.pinrepair.com/em/index3.htm#features
Example of a pinsider actually doing this https://pinside.com/pinball/forum/topic/red-baron-tech-question#post-5858156