Any advice on power button removal/power on issues?

Hey guys!

I'm working on reviving an iMac G5 17" Model A1144 and I've come across some roadblocks. The primary issue is that recently during normal use it randomly powered off a few times and then stopped being able to be powered on entirely. I know it's old, but I've seen Macs last well beyond this!

So far, I've replaced the power inlet, the power supply, the DC-DC board, and the logic board with no change in symptoms. None of the LED indicators have lit up throughout this entire process.

That means I've replaced all but two internal components that deal with powering up the iMac (I believe I took everything else into account, so correct me if I'm wrong).

Those two components are the DC cable (connecting the DC-DC board to the logic board) and the power button. I've purchased both of those components and am waiting for their arrival.

Does anyone have any advice for removing the power button switch board in this model iMac (I plan to test the new one before removing the old one, incase it's a destructive swap) or any other ideas on how to bring this iMac back with all the work I've put into it? Am I not seeing something obvious?

Thank you in advance, iFixit self-repair community!

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The #1 LED should at least light - even before you power on. That it doesn't points to the power supply and it's connections to the logic board. I think you need to look backward, not forward for the source of your problem.

The other LED's should also light in sequence as the machine powers on. IMHO swapping components after the power supply is useless until you know the power supply is working.

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Thanks for the advice,

machead3. Unfortunately, I can't get the #1 LED to light for anything. A bad power supply was my first thought, so I bought a working, used one to replace it. Still no light. Everything in this iMac has been replaced with working, used duplicates, but the symptoms haven't changed. I saw the #1 LED light up for a split second once, at the very beginning of working on this with all the original parts. I'm at a loss of ideas. There's too many parts and possibilities and not enough knowledge in my brain or leads that I can follow. What would you do in this situation?

Do you know/know anywhere I could get info on what the multimeter readings should be when testing the various power components (output from power supply, output from DC board, output from DC cable, etc.)? Other than that, I'm thinking of calling this an unsolved mystery.

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I don't have the information but look at no power all of a sudden, after replaced caps procedure for some. FWIW this model is notorious for bad capacitors - see any swollen or dark ones?

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Thanks for the resources and info once again! I did know that this model is notorious for bad caps and the new "used, working" board I bought has one swollen/darkened cap, which wasn't explicitly described at the time of purchase, so I'm thinking about returning it as non-working. The original logic board is in great shape with no bad caps, I just figured it was bad for some reason that I couldn't physically see. This is why I'm at a loss for ideas. I don't know which parts to test together now that I have duplicates of all of them, so it seems overwhelming. I'm going to try and test all the power components (starting with power supply output) with a multimeter tonight and see what I get. Your continued support has been appreciated for sure!

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