"Could be a lot of things..." How's that for helpful? :-)
First, don't try reading any more cards until you take a look at the friction roller for the reader - it's probably turned to goo unless somebody has replaced it. (Although I'm somewhat surprised it actually pulled the card through on yours...)
The problem could be as simple as a bad battery - have you checked the voltage? Tried running it from a bench supply?
The next lucky break would be a bad/dirty connection between one of the three internal boards, a dirty power or run switch, etc. That will require disassembly. If you want to try that, check out the guides
here. Disassembly requires some experience working on electronics and small mechanical gizmos. The guides provide enough information/photos to let you decide if you're comfortable with trying it.
If you don't want to try a repair, I'm sure you can sell it easily here or on the 'bay as a parts unit.
Regards,
Bob
Edited: 15 May 2011, 8:57 a.m.