My ti-84 plus ce turns off on bright white screen?

I cannot find my problem anywhere in the forums

when i turn it off it shows blank bright white screen

My Texas instrument calculator TI-84 plus CE Works excellent except for when you turn it off it goes off on a blank white screen .

when you turn it on it goes on normally however, when it is on you cannot adjust the contrast or the brightness of the screen, you cannot dim it or even make it more brighter .

please take note that all buttons are functioning properly

and I have tried everything

hard reset pressing second delete and back reset button

also trying to reinstall OS didn't work

also try to clear memory several times same thing

remove the battery for more than 10 minutes then put it back same thing

also try the self test the brightness indicator changes values on the screen but still do not dim or brighten

please advise urgent thank you