The cable I was using also went bad and I’ve marked it as suspect – its a distinctive pink cable. I’ve inspected the Mayfly USB c on Mayfly1.1 with an Eye Loupe, and it is hard to inspect but nothing jumps out, seems OK.
I did have a USB current monitor in the testing before hand, and the current had gone up to 1.2A while charging a 2.2Ahr battery – but difficult to know if it was related. However the Mayfly options are not set to do a high charge, just 0.5A.
I switched to Linux Ubuntu to get more details, and a sturdy USB-C interface and I get with working White Cable into Mayfly1.0
[20236.503620] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[20236.503624] usb 5-1: Product: EnviroDIY Mayfly USB to UART Controller
[20236.503627] usb 5-1: Manufacturer: Silicon Labs
[20236.503630] usb 5-1: SerialNumber: 0001
[20236.565048] usbcore: registered new interface driver usbserial_generic
[20236.565911] usbserial: USB Serial support registered for generic
[20236.586585] usbcore: registered new interface driver cp210x
[20236.586749] usbserial: USB Serial support registered for cp210x
[20236.586863] cp210x 5-1:1.0: cp210x converter detected
[20236.594710] usb 5-1: cp210x converter now attached to ttyUSB0
but then insert into Mayfly1.1 it doesn’t respond on the USB. It does get powered,
I think I have all the switches right, but here is a video https://photos.app.goo.gl/2n43i7qjLGmwbiQz7