It cannot detect both units. Only the working unit shows up, even though the strange unit is seen as a local device. Very weird. I can't even change the network name. I am guessing it is a partial low voltage power failure. The networking chip still gets power because I can see other devices. But I have no clue where this other password is coming from. It is not the password printed on the label and I have tested it with all other powerline devices removed. I would guess that a power regulator has partially failed, cutting power off to half of the board...but that doesn't explain the strange password. Do you know of cases where people have flashed the wrong firmware and gotten behavior identical to this?

@Solla-topee  Hi,

      The situation is very strange.  On the main page of the latest and older software, the adapter is not shown.  If I plug in a working adapter in my home, it shows on the new software, but not the old software, presumably because the firmware is not compatible with the old software. 

      Now, with all powerline adapters unplugged, if I plug in the one with the problem, I do not see anything on the main page of either version of powerline utility.  However, on the older Windows version of the utility, while I will not see anything on the main page, I do see something on the Local page.

     With the problem adapter plugged in, if I plug in a working adapter, I will see ONLY the working adapter on the main page. I can reset it and do all the things allowed by the new version of software and I can do all of these things via an adapter which technically does not exist. It never shows up on the main page.

     The device shown in Local has a MAC address which is not printed on the label.  The OUI for that MAC address is Atheros. There is an Atheros chip in the powerline adapter from what I have seen on YouTube.  This device also has a password displayed.  The password is not the same as the one printed on the powerline adapter. I have no idea how that password was displayed. Maybe it was something computer from the MAC address?  If I remove the problem powerline adapter and substitute a working powerline adapter, no such device with the Atheros MAC and unknown password is found.

     With the problem adapter plugged back in, it cannot be changed. The network name cannot be changed, it cannot be paired, it cannot be reset, it cannot be flashed.

     So, my theory now, courtesy again of YouTube, is that a filtering capacitor on the power supply has gone bad, but apparently there is enough power to run the ethernet chip because that clearly still functions since I can see working powerline adapters, even from other manufacturers, if they are plugged in.  Pretty strange.