Unable to use extermal 10" HDMI Display with the Orange Pi 5

[LiveRock]

Unable to use extermal 10" HDMI Display

I am stuck for a few days googling and searching for a fix.

The LCD works when it is connected to my Mac Book Pro The Orange Pi 5 HDMI is able to drive a big, Philps 22" 4K monitor Therefore, hardware wise, they are working. It is when my OPI is connecte to my 10" small LCD via HDMI. No output.

I trird doing the xrandt stuff but always get an error: "Can't open display"

doing " export DISPLAY=:0" gets: Authorization required, but no authorization protocol specified

Can't open display :0