Would that show stuff on the display itself too? Where are the UART pins and what are the pinouts?All Dahua VTO/VTH devices run linux. Off course u can connect to UART pins and see boot messages.
It‘s the same in that github issue, that board looks exactly the same and the port is at the same location, its just the other board that is different.Hard to tell, I don't own VTH1550CHW myself.
Can you open it's back and send me hires pics. Then I might be able to.
Here at least a starting point VTO1550 inside
Did you ever work with serial terminals,etc.?