What may be with my tablet?

[stodag]

Sounds like youv bricked it.. Use Odin.. its a flash tool and easy to use.. I'll get back with a tutorial.

http://mobilecon.info/flashing-galaxy-ta...-odin.html

It does work, I had the same problem with my galaxy s and galaxy ace..

Fyi:you'll need a PC and USB cable.

First acquire a stock ROM(download links on page linked)
Then run Odin,click PDA tab search for your ROM through Odin.. before you press start you need to put your tablet into download mode.. First power of tablet, power back on while holdin volume down.. should now be in download mode, connect your tablet via USB to your PC .. if Odin recognises you'll get a notification in the top left corner... Press start DONE

If your tablet isn't recognised, you will need drivers.

Edit: same goes for your s2 if that ever gets bricked.

No need to use the link I gave you, my tutorial will work.