A tale of almost disaster I thought you might enjoy:
Work kindly bought me £60 of RAM expansion this week, keen to see how faster it made this laptop I checked the laptop was off, took off the slot and changed the memory. Turning it back over I pushed the on button. Nothing. £600 of laptop not even trying to boot up. With icy dread I suddenly realised that it could have accidently turned itself on during my weeks travels and that the battery was dead so it would be in a hibernate mode where the screen shows nothing - it looks like it isn't on. Maybe I'd just changed the memory with the laptop still runnning...
The manual confirmed what a Bad Thing this would be 
. No amount of changing memory seemed to help, I was convinced I'd fried the motherboard.
While waiting for Monday and the Toshiba help desk to reappear I idly replaced the memory one last time, altering the angle I was trying to put it in at. I almost fell off my chair when the welcome screen appeared.
I didn't quite kiss the screen but it was close 
Richard