Was he properly grounded (i.e. an ESD mat or wrist band)? It only takes 10 volts of electricity to fry any component (an static shock that can be felt/seen maybe in upwards of 50,000 volts to put it in prospective). Assuming he was, was the pc unplugged from a power outlet/ power supply disconnected from the motherboard when he did the install, this can also fry things. Also, silly but most pc problems are, did he disable the on-board video in the bios prior to install and did he switch the plug from the monitor to the new graphics card slot and not the on-board one (hence no picture on but otherwise). These are just a few questions to help clarify the situation.