Iphone jailbroken, needs restoring?

I bought a used iphone, when I synched it to my itunes account, it worked and added my itunes apps and music to the iphone. I didn't activate it with a cell service, just intended to use it as an ipod. It worked for about 3 days, then it went to an apple symbol on the screen and sometimes a dead battery sign. It won't charge. I took it to a cell repair store and he said it had been "jailbroken" and would be too costly to fix. Does anyone have any other ideas or suggestions on what I should do?

Plug it into iTunes and restore

Being jailbroken wouldn't have a single thing to do with it not charging. Those people are idiots. Try restoring it with iTunes, and if iTunes won't detect it, even if left plugged into the computer for 10-15 min, then I'd take it to someone else who knows what the hell they're talking about.