My boss asked me to upgrade his son's CPU. It would never start. I checked the battery, the power supply, memory chips, and the cables. I finally pulled the 2 HD's hooked them to another computer and upgraded the OS. I put them back in the original CPU, nothing. The fans come on and I have a light, but there is no attempt to boot the HD at all. Would this mean the mother board is toast? I've replaced one other MB, but that was years ago when I was working for the school. I am limited on tools I have now. Is there anything else I should try?