You have to fix it from your computer. On your computer, download and install Samsung Kies application from here --> http://www.samsung.com/in/support/usefulsoftware/KIES/
Then download the correct firmware for your Tab from here : http://www.sammobile.com/firmwares/download/28954/P5113UEUCMK3_P5113XACCND2_XAC/
(In the above site, click Regular Download. You may need to create a free account in that website to download the firmware file. The firmware file is a big file so it would take a while to complete the download process)
After you have downloaded it, you will get a zip file. Open it or extract it and you will get a .tar.md5 file and some other files. The tar file is the firmware file.
Then follow the steps below.
Download the Odin application from here : http://www.mediafire.com/?7v7zor9d379emeg
or from here --> http://odindownloader.com/dload/Odin3_v3.10.6.zip
Odin application is the application that we're going to use to install the dowloaded firmware to your Tab
Then open Odin application and follow these steps below;
Put the Tab to Downloading mode. To do that, turn off the Tab. Turn it on and immediately hold down Volume Up and Power at the same time to boot into downloading mode. Volume Down to confirm if asked. This is just like you did earlier.
Then connect the Tab to the computer with the USB cable. A message saying "Added!!" will appear in Odin's message box at the bottom left of screen.
Click the PDA Button, and choose the .tar.md5 file (the firmware file)
Make sure Auto Reboot and F. Reset Time options are enabled. Also make sure the Re-Partition checkbox is not selected.
Don't make any changes to Odin. Click Start. Let Odin finish the process. Once it finished, it will show a Pass in the top left. Please let me know how it goes.
Make sure you download the correct firmware file for your Tab. Also when you do this, you will lose everything from the Tab. Let me know how it goes.
Refer this Youtube video --> https://www.youtube.com/watch?v=Ulz-1UYzHBA
(see the video from 1:07 onward after downloading Odin and firmware file)