Hello. I would like to know if you resolved this problem for i have the same problem. When i hit the start button and let go it powers momentarily then off over and over untill i unplug it. Im ready to throw it away. Thank you.
I am working on a 754n for a friend that has the same problem. I got it to power on by unpluging the power switch from the motherboard and leaving the powercord plugged into the power supply and connected the powerswitch cord to the mobo for an instant, just long enough to see a fan start turning, otherwise it would shuddown after 4 seconds. the problem is the switch, I took off the front panel and removed the switch. inspecting the switch, I noticed when I pushed it in, it didn't come all the way back out. I had to pull it out to hear the second click.
Unsolved 
