Does the machine reset correctly?
Do the coin switches add credits?
Are you able to read and understand schematics?
Are you able to post pics or video if needed?
One of the 1st things to check is the lock relay.
If it doesn’t pull in when the machine gets turned on and the left flipper button is pushed it’s coil might be bad.
You can interact with the ChatGPT Bot in any Chat Room and there is a dedicated room. The command is /ai followed by a space and then your ? or inquiry.
ie: /ai What is a EM Pinball Machine?