iMac 24" bad power supply - maybe capacitors?

Hi

We’ve a 2009 iMac 24” 3.06 Core2 Duo. It’s been sat on the shelf for a couple of years, but dug it out for my daughter to use and it has been working well for a couple of months - until this week. Apparently it had switched itself off overnight a few times, but switched on OK. Now it doesn’t switch on OK. We get the first LED when plugged in, then the second lights lights up for a couple of seconds, then the third and fourth lights flash on, fans briefly spin and a tiny chime, then all LEDS off. If I leave the RAM out it lights up 2 LED then just beeps for as long as I leave it. I thought this ruled out the logic board. I removed the display and still same behaviour.

Now I’ve removed the power board I can see three swollen 16v 2200uF capacitors (c205, c206, and another) - is this likely to be the problem and worth swapping them and trying again? The used Power boards on eBay are pretty expensive for a not guaranteed fix - and are also 10 year old. But I would like to get the computer running for a bit longer as it was working fine! I can’t see any cold joints on the board, but may have a closer look while waiting for the caps.

I’ve tried the easy fixes like SMC and PRAM resests and new button battery.

Anything else I’m missing?

Thanks!