S8 gone sluggish and White Screen when powering off?

[Android Central Question]

Hi

I downloaded a PDF although it looks like may be a virus. Since then my Galaxy S8 has went weird.

Very sluggish. Most apps take much longer than normal.
The My Files folder has nothing in it.
And I cannot power off or restart the phone. It just goes to a white screen and the only way to get rid of it is Volume Down and Power together. Help Please!!!

Thanks

 

[B. Diddy]

Welcome to Android Central! Force a shutdown like you've been doing by pressing and holding Power and Vol Down for about 15-20 seconds. Then boot into Safe Mode: https://support.t-mobile.com/docs/DOC-34283. Do the problems still happen?