First thing unplug the ROW connector from the CPU, if the error stays an issue on the CPU, if not you have an issue out in the game.

Were you working on the game before this ?

LTG : )

I sold my Indy and no longer have it in front of me to test, but there was one easy spot to ground out the game, and that is underneath the moving mini playfield on the upper left. If a ball bounces, it is possible to smush the wire of one of the diodes against another diode, caussing all sorts of weird issues in the game. This can happen during gameplay with a hard bounce into the scoop right before the ball draining without you knowing, or with your hands when you are installing something else. I'd pull up that mini playfield and visually inspect if any of the diodes were "smushed" causing a short.

Good luck!

Great looking IJ! Like you, Indy is my grail game. I've owned it for 20 years, and I'll never get rid of it. But I'm more of an Indiana Jones collector than a pinball collector.
That said, I noticed you've also tricked your Indy out with a ton of mods and other little additions, but your stand-up targets are still bare. A while back I made some custom metallic decals for my machine based on the treasures from the quick 2-ball multiball mode, and decided to make them available to other IJ owners who might also be interested. You seem like someone who might be interested. Not a sales pitch, just a heads up in case you missed seeing it elsewhere.
Metallic IJ Decals
https://pinside.com/pinball/market/shops/1262-pinjewels/03842-indiana-jones-metallic-target-decals-free-shipping-avail

Do what LTG said and report back

Did you try LTG's suggestion with j205/209 unplugged?

While you have the back box open take a picture of your MPU board and post it. Maybe your u20 is already socketed.

At some point someone socketed U20 on that board so if that’s what’s wrong, easy fix.

But we need a photo of the switch levels test with the playfield switch row header disconnected from the CPI board because that eliminates or identifies the cpu board as the issue.

U20 is a chip responsible for the switch matrix. At some point it was replaced because it's in a socket and the boards did not originally have that chip socketed. Looks like whoever did it did not have the right number of pin socket as you can see that one of the socket pins is seperate from the socket.

The reason we wanted to see the switch levels screen with the row connector disconnected from the CPU board was to see if the issue was on the CPU board or the playfield. If disconnecting the playfield switches from the CPU clears the ground row shorts we know that you have an issue on the playfield itself. At that point I would start disconnecting opto boards one at a time under the playfield to determine if one of the opto boards has a bad LM339 chip. For example, (I'm not sure I would have to open up my IJPA to look) I think that a Row 3 ground short can be caused by the opto board that is on the left side under the playfield about 12" from the front of the pin.

disconnect all the connectors at the bottom of the cpu board and see if your pin will boot.

Take a good picture of the battery area.

J206 and J208 does not get used you have J206 plugged in should be plugged in the lower one

Arent they just pinned together anyway?

Me personally I’m betting the OPs problem is going to end up being a playfield opto board

The socket is probably fine. Whoever put it in didn’t have an 18 pin socket so they used a 16 pin and 2 singles.

Agreed, LOTS of battery corrosion from some time before. Telltale dull solder all over that area below where the batteries were.

I am not sure are they ?

The start button not working could very well be a problem with the button itself.

Yep! Was about to ask OP to go into switch test and verify the physical switch is working.

Yup. Make sure it’s inserted correctly and make sure the bulb isn’t interfering with a full button depression

There's pretty extensive prior battery damage on the CPU board that was not cleaned up properly. That's the root problem, most likely. Get that fixed, then move from there.

Your DMD says the wire colors are right. The other two wires are for the lamp in the start button.

LTG : )

FINALLY!!! 26 days and we finally got a picture of the switch test screen!!!!

Look at the 2nd image you posted of the switch test.

Forget about the start button. You still have a full row 3 ground fault so no switches work on that row. Stop shotgunning and do the basic troubleshooting test that was asked of you weeks ago to isolate the problem to the playfield or the MPU.

With that test screen up on your DMD unplug the cabinet switch row connector from the MPU.

Do some of the row 3 boxes turn off?

Yes - at some place along the white orange wire path between the switches on columns 3 that wire has a path to ground. It’s pinched, has a screw sticking through it’s sheath or there’s a broken solder joint

No - you have a problem on your MPU board. Remove it from the machine, put it in a box and ship it to one of the many competent board repair people here on pinside.

For what it's worth, I had a similar problem on IJ years ago. Traced and traced and every test I did indicated it was the 10 opto board. I even replaced the LM339's. No go. Ordered a new replacement board and that fixed it and years later it's still working.

If we could eliminate the MPU as the problem the opto board is the next thing I would unplug.

MPU is the problem. Clear battery damage all over that area below where the batteries go.

Look closely at the IC to the right of U19. Battery damage under the green mask above and below that IC. So there is probably a lot more damage you can't see.

LTG : )