Texas Instruments TI-92 Troubleshooting
TI-92 replaces previous graphing calculators with its larger display, computer-style QWERTY keyboard, graphical user interface, 3D graphing features, and its Motorola 68000 processor.
Calculator does not respond to "on" button.
If your calculator does not turn on, first check the batteries. It is likely that the AA batteries simply out of power. Check this by replacing them with new AA batteries and attempting to turn the device on. You can see how to to replace the AA batteries here. If this doesn't work, you may have a bad OS.
If both your lithium battery and AA batteries are working, but your calculator still isn't functioning properly, remove one of the AA's. Hold the [APPS] key and replace the battery. While still holding the [APPS] key, turn the device on. If it turns on, the device will say something along the lines of "Press I to install code." If this message is given, press the  key. If the device gives a message about needing to install the OS, you will have to replace it.
If the previous suggestions prove to be no help, then you may need to check the lithium backup battery inside the device. This procedure can be shown in the guide "Replacing Texas Instruments TI-92 Backup Battery".
Screen is difficult or impossible to read.
The screen may appear to be faded if the contrast is too low. To fix this repeatedly press and release the Diamond key and the [+] key in succession. If this does not work the problem might be due to high contrast. In this case you need to press and release the Diamond and [-] keys in succession. If your screen is still difficult to read you may have low batteries.
As the batteries start to deplete the screen starts to dim. This might be causing the problem. To test to see if this is the problem, replace the old alkaline batteries with new ones. If the screen remains dim you might have some internal hardware malfunction.
Device shuts off while operating.
When the device is in use, but not being given commands, it will turn off to save power. This occurs after only a few minutes, so this is not actually a problem, as long as the device will still boot. Any information on device should reload when you turn it on.
If the device does not turn back on after it has turned off from power loss, it is likely that the batteries have simply run out. If this is the case, it is easy to remove the case and replace them following this guide . If this does not work, consider reading the troubleshooting guide for "TI-92 wont turn on."
Calculator seems to "lag" or act slowly.
Your memory may be filled up with set variables and programs; therefore, there may not be enough available memory to run programs or compute problems.
Screen appears overly pixelated, distorted, or damaged
The display inside of your calculator may be physically damaged. If you see dead pixels, or other warped images that are clearly deeper than the physical screen, you may need to replace the display. The guide for replacing the LCD display is shown here.
Screen appears damaged, but images are still shown.
If the physical screen on the outside of your calculator is cracked or otherwise broken, you will have to open the case and replace the plastic sheet that covers the display. Click here to see the guide relating to accessing and repairing the screen.
You press buttons but they do not appear to registered or have any affect.
Dirt or other materials may have cause the keys to jam or get stuck. This would prevent the keys from fully being pressed. To fix this go to the Keyboard Repair Guide.
There might be something blocking the keys from the contacts on the motherboard. In this case you will have to use the Motherboard Guide to access the motherboard and then clean off the contacts or remove anything blocking the keys form the contacts.