Hi I've had my late 2006 iMac for five years now and have had very few problems with it over the years - I had the LCD panel replaced by Apple last year due to a known issue and that's it. I use the iMac overnight to play audiobooks, and this morning I noticed I couldn't hear it burbling away when I woke up. It appeared to have switched itself off overnight, but then it wouldn't start up again. Nothing was happening at all - I checked all the cabling, including trying different power sockets and trying the mac's power lead in another bit of kit and vice versa - nothing at all. I got the service manual online and managed to get the bezel off to check the diagnostic LEDs. All appeared dead at first, which indicated that it needs a new power supply which is what I figured from the start. I read somewhere that removing and reinserting the battery can fix such problems, and since I tried this, diagnostic LED number 1 (indicating that the power supply is getting good power from the AC outlet according to the manual) now briefly flashes on at the point where the power cable is plugged into the mains, but then goes off again. Nothing still happens when the power button is pressed. Has anyone got any ideas on this? The manual is clear on the issue if the light doesn't come on at all, but I can't find mention anywhere about it coming on briefly. Many thanks!