Hey guys, a little help here if possible.

Twilight Zone with a colordmd and a couple of issues.
Original boards in backbox, except for a Rottendog driver board, which was just replaced. (We're troubleshooting that one soon. Using for parts during spring break currently)

Currently, the boot process is :
Turn power switch on.

CPU board LEDs on power:
D19 ON - then OFF
D20 OFF - then Flashing.
D21 ON

From what I understand, this is the normal boot process for the CPU board.

While this is happening I get a progress bar on the DMD, a "bong" sound, and ticks, progress bar goes away, leaving "testing..." and revision. Without batteries, I get "factory settings restored/high scores reset"

Menu switches don't work. Common is ok, tested from switch bank to side board to cpu board.

J205 connects these switches to the CPU board. I get continuity from the inputs there to the resistor/capacitors.
Those resistors and caps give normal readings.

Testing the other resistors, I get drastically reduced resistance on R67 and C11, as well as R69 and C13. Removing U20 and checking again, the resistance is back to normal values.

Ok. U20 is bad. Again. We've replaced a couple times now, as well as U13-19.
I'm guessing U20 is holding something low, and causing the test to freeze. Might have to replace U16/17 as well, to get the menu switches back, perhaps not. Is there something that I should check that frequently blows U20? I'm not keen on replacing these chips every time someone glances at the game.

On to the next issue:
I currently have J124 on the Rottendog board disconnected due to it blowing the F101 and F102 (3a slo blow) fuses when its connected. This connector goes to the High Power Driver board under the playfield. All diodes, resistors, and TIP36Cs test ok. High power board drives the following:
Solenoid 26- Mini play field right magnet (Tested at ~6 ohms)
Solenoid 27- Left Ramp Diverter (AE-26-1200 tested at ~11 ohms) (This solenoid and bracket came loose due to stripped holes. Had to fill the holes and reattach screws)
Solenoid 21- Left Magnet (Tested at ~6 ohms)
Solenoid 25- Mini play field left magnet (tested at ~6 ohms)
Solenoid 23- Lower Right Magnet (tested at ~6 ohms)

Anyone see any issues here? The resistance values seem ok to me, the wiring doesn't have anything obvious wrong.

Thanks guys!

Edit 3-11-19:
Replaced U20, U17 and U16. This fixed the low resistance on R67/C11 R69/C13, but still didn't boot past the testing screen.
Focusing on the other issue, J124 was blowing the fuses due to a melted LED flasher (inside ramp flasher). Removed the flasher, connected J124, and it boots, starts up... and blows the 3amp fuse for solenoids 1-8. Seems like some of the switches are stuck on as well. I can make it into the test mode now, so should be a bit easier to troubleshoot. Making progress.