That is all very odd because your dmesg definitely saw the OTG adapter, but I am not sure if it should show up in lsusb as a result.
Perhaps it is broken, as you say.
There is also a reference to ttyAMA0 in your dmesg.
I might have to find my Pi Zero and have a play.
I am using this setup and I had some issues with a bad cable before. Swapping the cable fixed it.
Also try the other port on the Pi.
I installed zigbee2mqtt on the PiZeroW and did not try the ser2net way.
There was something specific about the installation on the PiZero that was different to the method described. Ithink it had to do with NodeJS but it has been a very long time since I did that.
The PiZero is my only zigbee2mqtt hub.
edit I run the 2 command above, this is what I have:
> pi@zigpi:~ $ ls -l /dev/ttyA*
> crw-rw---- 1 root dialout 166, 0 Jun 23 11:15 /dev/ttyACM0
> crw-rw---- 1 root dialout 204, 64 Jun 14 16:22 /dev/ttyAMA0
> pi@zigpi:~ $ lsusb
> Bus 001 Device 002: ID 0451:16a8 Texas Instruments, Inc.
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
And that was it! Just tested with my new adapter:
pi@raspberrypi:~ $ lsusb
Bus 001 Device 002: ID 0451:16a8 Texas Instruments, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
It is working perfectly!
So frustrating to spend all that time and figure out you did nothing wrong!
LOL exactly! 