I'm using the TI-Nspire 84+ keypad.
I was moving the mouse in Doors CS to click on my tower defense game, when I got this weird error - everything froze and there were random pixels lit up. And the scrollbar is split in two.

Even after I do a battery pull, it still appears! As soon as I snap in the keypad, it appears! It does not respond to ANYTHING! Is there anything I can do? (The normal TI-Nspire part works though.)

I dont think a battery pull works try 2 things

1. Press the reset button on the back of the nspire

2. Go to nspire mode and resend OS. back when DCS nearly bricked my nspire (thankfully fixed) this worked.

or:

3. Dont use the TI-84+ keypad, get a real TI-84+ if money is not a constraint

I had this happen a couple times. Ok. pull all your batteries for 60 seconds to 2 minutes. Hold the reset button as you put the batteries back in. Helps in you have a friend help you.. Keep holding reset until after the keypad is in and turned on. If that does not work then do the same thing but put in the Nspire keypad. That will force a reset in the Ram since it has to change OS from 84 to Nspire.

That doesn't work at all. Whenever I hold in the Reset button, the calc is off until I release it. It won't turn on while the Reset button is held.

Out of curiosity towards making sure the problem doesn't recur, what is your Tower Defense game written in? The TI-Nspire's 84+ emulator is notoriously badly-written, and crashes on "undocumented" instructions. If your game is an Axe program, then it may have generated such undocumented instructions. Either way, I hope you're able to unfreeze your calculator soon.