I have tested my touch monitor from computer kit touch and couldn’t get it to display an image either.
I powered the video driver board for the screen and the Pi with different power supplies to make sure the display would work off the supply.
When trying to display from my laptop on the touch panel I even connected the touch USB to my laptop thinking it may have some interaction to make the displays work.
The touch did affect the cursor on my laptop but the display didn’t show.
My laptop didn’t recognize the screen in device manager or the screen resolution settings or using the Intel Media Graphics and Control Panel.
I also couldn’t get any information from the registry using Extron Edid Manager program which displays EDID information for any display that it recognizes.
I connected a Sony BlueRay player and it displays Sony and BlueRay splash screen but movie doesn’t show.
I tried a Blackweb composite to HDMI converter processing a VHS tape and it displays on the panel.
When I plug in the converters power the video says AV NTSC and when I plug in the HDMI cable it says 720P.
Plugging this signal into my TV, it shows 1280x720@60Hz.
It may be that the display is looking for a 720P @59Hz signal that my TV reports as 60Hz.
I believe that there are differences between TV and PC signals that some displays can’t show both of.
Converting NTSC to HDMI may produce 59Hz refresh where the Sony BlueRay HDMI out may be the same until the movie plays at 60Hz. The Sony doesn’t have composite out to see how it converts, neither does my LG BlueRay.
Anyway the panel can show video if it is the right format.