Hi, perhaps the ribbon cable connecting the motherboard is partially loose. Just to be sure, I’d like you to run a self test
- Turn the calculator on and put it on the home screen
- Press [mode]
- Press [Alpha]
- Press [S] (the ln key)
- Press [enter] four times (congratulations, you’re now in the diagnostics section!)
- Press [on]
- Now your calculator should be displaying different patterns on the screen. Press [enter] to cycle through all 45 or so patterns and contrasts, please tell me if the bottom part of your display works for any of the patterns.
- Press [on] multiple times to exit the diagnostics section
If your screen still doesn’t work, I’d suggest looking at a topic on ribbon cable repair which you can find here.
Good luck, please let me know if you have any issues or questions!