Power issues with late 2009 iMac
Sorry for the long post, but I'm trying to be thorough.
I may have done the bad thing. I came in to get set up for an event yesterday, only to find that my iMac would not power on. No chime, no whirring of a disk—nothing. It has done this before, and the only thing that helped was to leave it unplugged for a week, then try to boot up a week later.
Side note: I was out-of-state over the weekend and don't know if there were power outages/surges from weather, but we'll consider it likely.
Well, I decided to open ‘er up today as I had seen that there are diagnostic LEDs that can point to the issue. I got the screen off and delicately set it aside only to then discover that I was looking at the troubleshooting guide for the wrong generation and my LEDs are visible through vent-holes without removing everything. I decided just for kicks that I would unplug the power supply from its cables and plug it back in. Got everything screwed back together, screen put on, and it started up!
Now, though, the display is a bit messed up and I'm not sure what went wrong… everything displays and I can use it just fine, but green dots and stripes show up in varying places. The pixels aren't dead; when I hover the cursor over any of those spots, they disappear and show up as soon as I move it away.
My question is twofold: 1) should I bite the bullet and buy a new power supply even though it booted up this time? And 2) how do I fix the green-pixels issue?
Any help would be appreciated!