My screen is all white.

This does sound like water damage so immediately stop charging the calculator and remove the battery! That way you can avoid accidentally shorting out the calculator and permanently breaking it (I’m hoping that white screen is a software error that can be fixed later). Remove the back cover of the calculator using the teardown guide and dry off the PCB as best you can (make sure to get underneath the aluminum foil). If your calculator isn’t under warranty, then you can go ahead and break the heat melted bits holding the PCB to the front shell. That way you can make sure the front of the PCB, the rubber membrane, and all the buttons are dry.

I’m not an expert at water damage so I would appreciate some guidance from the iFixit community for the following steps.

(As I said above, I’m no expert so this next step may be unnecessary, but it won’t hurt the calculator to do it anyways) From there you should clean everything with at minimum 91% isopropyl alcohol (aka rubbing alcohol) (higher percents are better). Then you should stick everything in rice for several days so any water has time to evaporate. After several days, you can take everything out and just to be safe, clean it all again with the isopropyl alcohol.

Once you’ve put everything back together (let me know if you need help with that), then you can put the battery back in and try to turn it on. If you still get a white screen, try some Técnicas de reparación para TI-84 Plus CE If it still doesn’t work properly even after trying that guide, let me know and I’ll have you try some troubleshooting techniques to see if it’s hardware damage.