Wii U Gamepad won't respond!

I got my Wii U around 2013, and about a year ago(2016) it just started to not respond. I asked my siblings if they done anything to it, they said no, which I'm guessing they did something to it because my little sister used it a lot then stopped.

The Wii U in the app selection menu doesn't respond as it should. The D-Pad, ABY buttons, Start/Select, Analog sticks, and I think LR too don't respond. Only X for the switching to the plaza thingy. Touch screen doesn't work either. If I want it to start working, I would have to give it a smack in the center of the screen, then it would start to work for a little bit.

IN GAME, Breath of the Wild for example, it works, the controls everything, but when a text display comes up or in the pause menu, the buttons don't work, again have to smack it a bit. When I play on the game pad itself and not the TV, it will glitch on its own back to the TV, and I have to hold the touch screen for 2-3 to play on the game pad and not tap. Mario Kart it glitches back too.

I did take out the battery for 30 seconds to a minute, it works for a while but then goes back to its not working state. Also did do the touch screen calibration and it works for a short while, then back to its not working state.

Please help with this! It has been doing this for about 6 months, and it's really really starting to get annoying. I can provide pictures if needed :D

Thanks in advance!