Well the title mostly explains itself, when i go to start up my iMac it turns on does its chime, waits about two seconds and then dies. If I unplug the machine and wait for a little bit i can make it do that again. Before the iMac "died" I was using Apple works 6 on Mac OS X 10.2 and it had gone through many install processes and I had to keep unplugging the thing because the CRT was turning off unexpectedly multiple times, sometimes it would turn back on and shake, but mostly it turned off and there was nothing i could do! So I had to unplug it! After installing the OS and updates and the unplugging multiple times I think it died, my bad. So from the symptoms and the circumstances, what should I replace, or try to do to fix it.