Device descriptor failed after USB board change

Hi guys,

I had a secondhand Nexus 6P that I bought, and it had a microphone issue (but was working perfectly fine otherwise, connectivity via USB was perfect, phone reception was perfect).

I had bought a new USB/microphone board and had a shop switch the two. The microphone issue is now no longer a thing, but it doesn't charge properly anymore (hardly draws any power from a computer USB port), and is no longer recognised by any computer (shows device descriptor failed in Windows 10, and error 43 in Windows 7). I did have it rooted before I switched the boards to see if I could resolve the microphone issue without a hardware change.

I do notice that my default.prop says "persist.sys.usb.config=none" and no matter how often I change it, after a reboot it reverts to that. Adding the correct line (=mtp,adb) to the build.prop stays, but doesn't change the issue.

I first thought it was just a bad board, but a second board that I replaced myself has the exact same issue.

Am I missing something? Is there a setting in the OS that I need to change for it to detect a new USB/microphone board?