Quote -
"I've got a 3630 and I think it's great. The battery is dead though because I forgot to flick the little battery switch to off when I went on holiday. I'll have to send it to Compaq to repair."

Dont send it back just yet. Try charging it for awhile. This happened to me, I thought I killed the battery (wouldnt go by 0%) after about an hour of being on the charger the battery started charging.