It seems like it was not rooted correctly. Did you run titanium backup after rooted?
Can u tell us what was the latest working firmware u had? FROYO,,GB? 2.2, 2.3.3, 2.3.6?
Anyways, Follow these steps carefully to fix almost all kind of softbrick:
1a. Download Fus Check Downloader 2.1 on your computer from url]http://fus.nanzen.se/[/url] , start it up and and downloaded a Firmware for your region. It will automatically decode the .enc2 file to.zip file
1b. Download this pitfile from following link:
1c. Download this dbdata from the following link:
2. Extract the .zip file generated from decoding file to a folder and I got tar.md 5 file.
3. Start Odin - put the .md5 to PDA
Put the pitfile from step 1b to the PIT
Check repartition. Leave everything else as is.
4. Go to download mode on the G-tab, connect to ur computer
and click start on Odin. It takes about 6 to 7 minutes to do the flashing.Once done flashing it will reboot but mostlikely you still have problems with your tab.
5. on your Odin, put the dbdata file from step 1c to PDA, leave everything else as is.
Reboot your tab to download mode, connect to computer, and click start on Odin.
6. Once done, reboot to recovery mode, do a factory reset wipe, and data cache wipe.
Reboot again, wait for about 5 minutes for the tab to boot, you should be all set.