|The intrusion alert can be cleared and, I think, turned off in cmos/bios setup. There's going to be a little switch connected with a 2-wire cable to the motherboard. When the case is opened, the switch changes state and the bios knows the case was opened. Just disconnect its wires from the motherboard and you won't have that problem.|
The error 8602 is a keyboard error. Causes I googled include mashing too many keys when it's posting, bad keyboard and keyboard plugged into the mouse port by mistake.