Without checking every wire is in the right place the Rectifier board looks fine just need to replace that resistor.

That MPU hack is the battery I think. If you removed it starting the game would be fine it just wouldn;t keep settings....but again that rectifier board needs a new resistor first

You can check the wires and more info here

http://pinwiki.com/wiki/index.php?title=Bally/Stern#Rectifier_Boards

Edit: the other red wire is probably just jumping through hole?

It looks like the batteries were removed after they leaked and it was not cleaned up properly.

That "battery" replacement is the strangest.

Also, I can't tell if it is the angle, but it looks like disc capacitor C30 on the MPU is blown in half.

Yeah they got it off the board at least... Kind of

Both of the resistors on the Rectifier board look damaged (one cracked, the other completely missing all the insulation). Hard to tell if MPU board is OK but showing lots of corrosion. The light driver board (LDB) also showing lots of corrosion (see all the green tabs on the SCR's going roughly in a straight line from the top of the board all the way to the bottom of the board).

I have several stern/ballys from this era I have found it is much easier to just get a repo MPU board and be done with it when it comes to MPU alkaline damage. The time and frustration saved is worth the 200 you will spend. That being said your power rectifier board doesn't look to bad and could easily be fixed. Also repinning the connectors on your MPU and power driver board will also make your life easier as well. Good luck my Tident was my first pinball I played and have had one in my collection for several years it is a great game...
Good luck with it.
Al

They both look much better than every board that I have repaired.....