So I bought an IBM ThinkPad T23 on eBay, it's quite nice, seems to work fine, cover is a bit dirty but I can clean that up.
Anyway, I had to buy a universal laptop AC adapter because I didn't have a 16V supply that it needs. The adapter came with a microswitch on the side to switch between 15, 16 and 19.5V and I think I accidentally gave it some 19.5V because I plugged it in, the light on the adapter was flickering, and the off button on the ThinkPad wouldn't work, at all, even for a hard power off.
So, do you think I've screwed up? It still seems to work fine, but do you think I've broken any components?