So you pull your trusty TI-83, TI-85, etc calculator out of the closet only to find that it is apparently no longer working. Powering on displays nothing on the screen. Changing the AAA batteries and the lithium battery improves nothing.
Before giving up and junking the calculator, there are two things you should try.
1. Adjust the contrast. For some reason, TI-8x calculators seem to be prone to having their settings corrupted and the contrast zeroed. This is probably the case if you can still communicate with the calculator through the parallel link. To adjust the contract, power the calculator on, then (blindly) hit 2nd, then hold down the up arrow. It should take about two seconds for the screen to become visible. If not….
2. Reset the calculator to factory settings. One way to do this is to remove one battery, and hold ON for 10 seconds. You can also remove all the batteries and wait several hours.
3. Reset the calculator using self test. Press 2nd, Mode, Alpha, A, Enter. This will wipe the calculator memory.
If for some reason you need to open the calculator to try component swapping, there are exactly three screws; two short ones at the bottom, and one long one for the lithium battery. After removing all the batteries, the calculator will pop open with some effort.