If all the lights are out behind the backglass, it is either dirty / mis-adjusted contacts on the Lock relay OR the plugs that connect to the back box (called Jones plugs) need to be cleaned and reconnected. Remove power, remove plug assemblies, clean carefully with a scotch brite pad, wipe with isopropyl alcohol and reassemble. I also clean the sockets.

The 100K light is a separate issue, but I would not tackle it until you get all the lights working.

Your schematic has been dissected here with great explanation by memeber @Xsyvtoys. Do a search and it will step you through everything.

The lock relay is cooked. Pretty common because it is on all the time. I see switch blades bent in the lock relay. I would straighten them and adjust for good tension when closed. You will see 2 larger sets of contacts on the lock relay blades. 1 pair is for backbox lighting and one pair is for playfield lighting. Make sure both are clean and closing tightly.

Check fuses and fuse holders. If you haven't replaced fuse holders, do it. They are garbage at this point.