What you need to do is-
1. Get the USB drivers for your tab.
2. Install ADB - look around on google, you'll get it.
3. Connect USB and change directory to ADB folder.
4. type "adb reboot recovery" in the command prompt.
5. Do a factory data reset - you can do that once recovery mode boots up by the above command.
If it doesn't work, look for firmware and post if you find it.