GPD Pocket 7" Screen Problem

Hi

I am one of the owner of the GPD Pocket 7". I am not sure what I have done, but lately, when I boot up the GPD Windows 7", the screen is always blank. I know there are activities, but the screen remain blank (black). So, I plug the USB-C to HDMI, to my Toshiba TV monitor, the GPD Pocket 7" is working perfectly outputting the screen to my TV monitor. But it failed to show anything on the GPD onboard screen monitor. When I touch the screen the touch screen still works. Very strange.

May I know how do I fix this problem? I have gone into Settings-Display and trying to change things there, but it does not seems to have anything there that could help this.

Please help. Thanks.

Ken

I have the same problem how fix it please