The screen turns on but it stays white with random colored lines

Oh, that sound fun.

So obviously RAM resets aren’t working. Have you tried charging the battery all the way? That’d probably be the easiest possible solution. However, I don’t think it’ll work.

In the event that it doesn’t work, if you connect your calculator to your computer and open TI Connect CE, does your computer recognize your calculator is connected? If so, it may be strictly a display issue. If not there may be something more serious.

If that still doesn’t work, try to reinstall the OS. It’s hard to provide accurate instructions through this answer box so I’ll refer you to a calculator recovery guide. The OS reinstall process starts at step 4. There’s also the guide in video format at the top.

If you get your calculator back to working state, you can see if it will likely happen again if you go into Self Test Diagnostics. There’s a video about it here, you should at least run tests 6 and 7.

What did you do to the calculator? Did it just randomly happen? Did you accidentally drop it or spill something on it? If you still can’t get it working, please reply and I’ll do my best to help you. However you may want to contact Texas Instruments Support and exchange it for a working calculator if it’s still covered by warranty.