Changed out both the back up battery and the 4

Hello,
When you change the batteries the display reverts to default setting. My optimistic guess is that the screen display is so light that you cannot see anything on it. This can be arranged.

A Try this before thinking of repairs.

1. Push the ON button.
   
2. Even if you see nothing, press the [2nd] key and release it.
3. Press and HOLD the UpArrow key until the screen darkens.
4. You may have to keep pressing UpArrow for a little while before you see anything.

B If that does not work

1. Remove one of the AAA batteries.
   
2. Press and hold the [CLEAR] key.
   
3. Whileholding [CLEAR], reinsert the AAA battery and then
   
4. turn the calculatoron.
   
5. The calculator should display the message "RAM Cleared".
   
6. Release the [CLEAR] key and then press it one more time to remove the message "RAM Cleared".

C. Third option

1. Remove batteries including the backup battery for 5minutes.
   
2. After the 5 minute period, reinsert all of the batteries and
   
3. turn the calculator on.
   
4. Adjust the contrast if necessary.

D. Last option

The last option requires the reinstallation of the system. So to use it you must download the TIConnect 1.6 software from education.ti.com. You must have the TI USB SilverLink or the TI Black serial cables ready.You must be connected to the Internet.

1. Remove one of the AAA batteries.
   
2. Press and hold the [DEL] key.
   
3. Whileholding [DEL], reinsert the AAA battery and then
   
4. turn the calculatoron.
   
5. The calculator should display "Waiting...Please install calculator software now".
6. Connect the TI Connectivity cable between the computer and the calculator.
7. Click on Start >> Programs >> TI Tools >> TI Connect >> TI OSDownloader.
8. Follow the on-screen directions to reinstall the calculator's OS.

If the message "Error! Press any key to turn unit off. Then turn unit backon." appears on the graphing calculator, quickly, remove one batteryfrom the calculator and reinstall it while the transfer is taking place.

If all else fails you can contact Texas Instruments at ti-cares@ti.com

Hope it helps.
Thank you for using FixYa.