Not a mod as such, more a repair.

I picked this thing up for free. No cracks in the panel, so I figured I might get it running.

When I plugged it into a DA G4, the thing was utterly dead. Wouldn't even try and boot. Brief flash behind the displays power button. I took it apart to check for loose connections, nothing obviously damaged.
Tried it again with a G4MDD same thing. The power button would not even light up when pressed with the display connected. In the MDD, I noticed that something started to make a regular ticking noise in or near the front panel board when pressing power with the display plugged in. Had to unplug the power to stop it.

Any thoughts on how I can get this thing working?
Anyone know where to get parts for one of these?

Try turning it on in a dark room and see if any picture comes through for that brief flash. You can also try a flashlight on it (the opposite of course). Something to test if a picture is coming through. It could be something as simple as the display inverter, though I never remembered hearing "clicks" when I've dealt with them in the past.

Since it does power on for a brief second, that does provide some hope. Tell us what you find out!

Doubt I'd get any picture for the brief 'flash'. Since the G4(s) won't even try and boot.

I'm guessing the issue is one of power. The clicking sounds like a spark or maybe a switch or relay of some sort. Like something is misfiring.