the miner must be still ok since there is no hardware damage and was functioning fine a week ago. I think the adafruit type cable might be defective and you have to order one from china on ebay with a converter+cables. but the detect utility is showing a signal from the USB-serial chip, I'm getting output from putty but no echo when I type.
Am I supposed to attach only TX-RX, RX-TX no ground?
I wrote to bitmain but I can't get an echo on putty or shellx, all the new drivers are installed all the port settings are as described xon/xoff
Ask Bitmain to do a remote session to help with this. You can ask in a ticket or even over phone depending on country.
But try this and see what happens, hopefully they will help.