I need help. The screen of my dna60c will darken when I press the ignition button.

[lao]

Excuse me, my dna60c screen will darken when you press the ignition button. After releasing the button, you can return to the original brightness. My power is 19 watts. The battery is also sufficient. I also used a new third-party theme. What is the reason for this? I'm using the translator to talk to you.