My preference was to share this with Schneider Electric / APC directly, but I couldn't find an email address, so I thought I'd leave this here in case others experience something similar.

I recently bought an APC Back UPS, model BVK750M2 (750VA/410W), for a small Proxmox server. I spent days trying to get the UPS's USB port to be detected, even trying older devices with USB 2 and 1 ports, but none seemed to detect this new UPS.

I'm in a very remote area, and this device is heavy, so I really wasn't interested in shipping it back to return it. In an act of desperation, I simply disassembled the unit. The rear USB type B port is mounted on a small PCB, with a white 4-wire cable that connects it to the main controller board. I thought I'd start there, testing each of the 4 wires for continuity.

Once I pulled that little white cable, I quickly noticed the issue. One pin was simply not set into the connector housing (see the picture). I pushed the offending pin fully into the housing and reconnected the cable, and now everything works as expected.

I'm not recommending that people start disassembling their UPSs. I'm only sharing my experience in case others are experiencing the same thing. My take-away from this is that APC does not test these units after assembly, because there's no way this USB port would have ever worked.

Stay awesome, Home Lab community!

https://preview.redd.it/m0807yz5g32c1.jpg?width=1575&format=pjpg&auto=webp&s=7cb75070a25415b17a726d7fabe8890afe07c0dc