When I take it to a shop they are able to test it on the bench and even turned it on using my power cord and monitor. But when I take it home, the light and fan come on for a few seconds before turning off, then goes on and off until I force it off. This happens in all the outlets in my home but doesn’t happen at the computer shop…could it be a problem with the power at my house? My other desktop runs fine here. I can’t think of any other differences between the setup at home and how we had it at the shop.
More than likely, its the power at your home. Since one of your computers is working, you can try swapping the power supplies. If the one that didnt work now does, and the one that did work doesnt, than the offending power supply is having an issue with your home’s power. You can buy another power supply and try it out. Alternatively, you can get a UPS that cleans the power and that should also work.