Issue with New build

[infinitLoop]

have you tried that other usb connection on the board?

basically, the v3 board is a 4-port usb hub that has a arduino mounted on it, that connects to the button inputs, and a usb soundcard, and then those two open ports. that's essentially what those different rectangular components are. you can poke around with a continuity checker to see where the pins map to if you wanted to try hooking in at different spots.

are you are still having the issue where when you plug in a usb device, and it powers off or reboots? if it powers off, then that sounds like something bridged, but reboot is a current issue (and shut down could be too)... the 1000c can do 1A, and a power-hungry screen, on top of the other stuff on the board, can definitely get close to that.

one way to check if its a current issue is to get a good external power supply, and plug it into the pi (not the powerboost). that will allow for more current, so if things work that way, then current is probably your issue. if that's your issue, you could get a better psu, get thicker wires, or shorter ones, or just eliminate jst connectors and other things that could cause a bad connection.