Hello,

I have a problem with the display powering on. When I press the power button it takes from 5 to 10 sec for the display to light up.
The same it is when i have a call over 1 minute and when i remove the phone from ear i have wait 10 sec for display to light up and I can end of the call

Any suggestions?

You can try to get a firmware update or do a factory reset to see if still have the problem.

Do you use the stock launcher?
Sometimes I have the same issue, but until today I can't link it to a special app or action that is or was running on my phone before.
I woult try to install a different launcher first. I'm using Line-Launcher and I have this issue once a week or so.