Several months ago I started a similar thread, thinking the micro-HDMI port on my pocket might have detached from the board – I was absolutely wrong, and I had a faulty cable.
Since then I’ve upgraded to the newer motherboard + sound board with the extra m.2 port, but this morning, alas, the external monitor I was using went black, and when I checked the port I found that this time it really has detached. 
While obviously this is sad, I hadn’t actually gotten around to testing the cellular modem, so I might go back to my original MB. The tines on the port seem kind of bent, so I’m not sure how feasible reattaching would be for my measly soldering skills.
EDIT: The new m.2 audio board came with an RCORE carrier board replacement, not the motherboard! So I don’t have an old board to go back to. Still not the end of the world, and it is probably repairable, although not necessarily by me.