My Samsung phone display wont turn off.

[Dendrobates]

My display sleep setting is on 15 sec but when I turn my phone off it stays on my lock screen and won't turn off

 

[mustang7757]

Hopefully hasn't been wet

 

[J Dubbs]

I try about 4 times to put it in safe mode and it didn't work. I didn't see the symbol to put it into safe mode. I took the case off for 20 minutes and the display still wouldn't turn off do you think I need to leave it off for longer?

Clean that usb port then a factory reset if that doesn't fix the problem