what is jailbreaking and does it damage the device...

Yes, it can. You're uploading unauthorized software to the device, which could have any kind of code running inside it. You bypass the security aspects of the iPad, which normally protect your device from hacking, data access, or other intrusions. Jailbroken devices are vulnerable to remote access (key logging) and the like. And neither Apple itself, nor these forums, can help with problems on a jailbroken device.

Matt

There are some additional suggestions in this Apple support article that may help:

http://support.apple.com/kb/TS1538

If not, including putting the iPad into Recovery Mode, try a complete removal and reinstallation of all Apple software. If that still fails, try a different computer. If it fails there as well, then the iPad may indeed have a hardware failure.

Note that this presumes that you have not jailbroken your iPad. If you have, then you're on your own.

Regards.