Posted 23 January 2013 - 09:55 AM
That sounds like once to me also (it wouldn't hurt to contact HP to verify)
one blink means CPU trouble (not good)
I am not sure if you are ok with this, but if it were ME, I would suspect that the CPU fan is not working and I would take it apart to verify.
Most equipment have a safeguard to prevent overheating (sometimes works, sometime doesn't). A signal saying there is no fan attached may prevent the machine from starting up.
When it would run for an hour and then quit I would say it was getting hot, so there is still the chance that the CPU is baked, but you may be lucky and a fan may get it to boot.
This is one theory, we invite others.