Why can't I wake up my phone since upgrade to Marshmallow

[AC Question]

Please help me, guys. This morning I upgraded my Android from Jellybean to Marshmallow (6.0.1) and when I turn off my screen with the power button and it cannot be turned on anymore. While being off, when I press the power button nothing happens(at least seen) but because I have a password and when typing it the phone vibrates, when I press on the black screen where the keyboard is, the phone vibrates so I guess I can do everything but I cant see it...so the only way to turn the screen on is to restart the phone and I must not turn it off even when not using it because it cannot be turned on anymore without restarting....please help. (USING HTC DESIRE 820)

 

[Golfdriver97]

Welcome to the forums. Have you tried going into recovery and clearing the system cache?

 

[kokicha120]

Hi! This is me, who asked the question, I have just made an account. So YES I did this and nothing different happened.

 

[Golfdriver97]

Welcome to the forums. The only thing I can think of is to try a reset. Who is your carrier?

 

[kokicha120]

what do u mean by "carrier"

 

[Golfdriver97]

Who is your provider for cell service?

 

[kokicha120]

M-tel

 

[Golfdriver97]

You may want to try a reset. However, this may be a different issue and the stock rim may need to be reflashed.

 

[kokicha120]

How to reflash the stock rom?

 

[Golfdriver97]

HTC may have your stock ROM files on their website. Under the support section may be a download section where you may possibly find your files. You will need a Windows PC to do this. The procedure is pretty easy. Unzip the file, open the .exe program and everything else should fall into place.

 

[kokicha120]

It seems like the only stock ROM files on the site of HTC which is missing is for my Desire 820....It is just missing there...How am I supposed to find it?

 

[aximtreo]

as a last resort before flashing, press the Power button and hold until you see some action on the screen. This may take 10 seconds or longer. If this doesn't help, flashing may be your only hope.

 

[Golfdriver97]

It seems like the only stock ROM files on the site of HTC which is missing is for my Desire 820....It is just missing there...How am I supposed to find it?

You can try a site like XDA. There are often stock ROMs posted. Barring that, you may need to contact HTC.