Updated Firmware - Extender Does Not Connect Properly on EX7000 Extender

I've had an EX7000 AC1900 Extender/AP since the Fall of 2016, working very well with my Asus RT-N66R Router. Once in a great while, there would be a drop, but I was always able to reconnect. Today (10/18/17) I was having a problem in the room where the extender is located (far bedroom on single-level home). I connected an Ethernet cable between my laptop and the extender and requested the "mywifiext.net." The new "Genie" opened and immediately advised I needed a firmware update to v.1.0.0.50_1.0.102, so I proceeded with the upgrade and that's been the end of any dependable connection between the two. I've performed two complete resets on the Asus router and four on the Extender. Sometimes the wired connection between the laptop and extender worked, but the wireless failed. Then the wireless worked, however when I attempted to connect to the Extender's signals, I would repeatedly face a "incorrect password," error. Of course, I validated the passwords on both units multiple times and they are a match as well as verifying that I am correctly entering the password each and every time. Does anyone know if there is a problem with this version of the firmware? I'd really appreciate some positive advice (other than going out and buying a newer set!) Thanks!