Perhaps a Prime Problem

[Claudio L.]

(01-22-2016 09:58 PM)ttw Wrote:  The PC is totally dead. I'll just try to use the Prime as is.

I did read that using the USB to charge something (which I have done many times on that computer) can destroy the computer in some cases; usually this is because the computer doesn't have proper internals.

I don't think a USB device can damage your whole computer. It's more likely some secondary chip that crashed and needs to be reset.
Are you using a USB powered hub? I had 2 of those after a couple of years of use started sending strange voltage into the PC (2 different hubs on 2 different PC's on different years), and the PC would refuse to boot. In one case, powering the USB would also crash the NIC (internal), so every now and then, when it allowed it to boot, the network would be dead, I had to pull the power completely to the PC to reset the PHY.
Perhaps your prime isn't the problem. Perhaps there's another USB device that's damaged and draining a lot of current, and connecting the Prime on top just makes it go over the limit and crashes something in the motherboard.
Unplug all devices (even the network cable), remove the power cable and press the power button to discharge any capacitors. That should reset the motherboard completely.
I have an old PC that drains power from the ethernet cable (is not POE enabled, I think it's damaged, it wasn't like that when it was new!). Even if I unplug the power, the motherboard remains ON, and pressing the power button flashes some LEDs indicating a power supply failure (of course, since the power cord is not connected!). If I unplug the network cable, the motherboard dies completely when I press the power button.
Unplugging everything makes sure your motherboard can't get power from anywhere, allowing all chips to reset themselves.
Try that and there's a good chance your PC will come back to life.