SuperMicro won't boot (won't POST) after trying to modify GRUB

Question

I have a SuperMicro in this configuration. We installed Ubuntu 12.04 on it and I used it for over a year until finally upgrading to 14.04. I upgraded from CD choosing only default options, and the boot failed, sending me to the GRUB rescue prompt. From there, in the course of trying different things, I set it to boot from minix--that is, I did something like

grub rescue> insmod minix

and immediately thereafter, the machine wouldn't even POST.Hmmm, I guess that wasn't a good idea. I've found various threads about non-POSTing machines, but never one where a machine that was previously running stopped working. In my case, it's gone from working to not working with no change to the hardware configuration of any kind.

I'll break open the box if I have to, but if there are solutions that don't call for that I would like to try those first. Needless to say the computer won't read boot CDs, although the optical drive is activated when I power on and the LED for the hard drive flashes briefly.

Answer 1

Ok, well I unplugged the power cables and let it sit for about 5 min., during which time I also got a little vacuum cleaner and vacuumed out the dust from behind the front outer panel. And voila, now it POSTs and I'm back to the GRUB rescue prompt.