I have this unusual problem with my Lenovo PC. A couple of years ago, my PC suffered water damage, and it wouldn't start up. I took it to GeekSquad to see if they could repair it. They said the motherboard was damaged, so I bought a new one and replaced it. It powered on just fine, but for some reason the keyboard and trackpad don't work. There are some weird circumstances in which they do however. The laptop is a 2 in 1, laptop/tablet. When the laptop is bent so it is a little past horizontal, the keyboard and trackpad work. Also, in startup, I can enter BIOS without having to use an external keyboard or mouse. I've tried updating the drivers through device manager, but all the drivers are up-to-date. Does anyone seem to know what is going on? (My laptop runs Windows 8.1, I don't know if that is useful information, just letting you know).