I'd start by having your friend check to make sure the right RAM was installed correctly and everything reassembled in the same fashion...
Is this the first time it failed to start up since the hardware change?
Hi, I've got a Dell Dimension 4700. It's starting up but I can't see anything on screen. If I press a button on the monitor it says it's in power safe mode but neither the mouse nor the keyboard seem to be working. The fan is going but I can't hear the usual churning noises.
Probably relevant: a friend added some more ram a week ago and I've been having problems with my network card - I sometimes need to press the network cable in to get it to work.
I'd be grateful for any advice.