I also reached out to ecotech directly. Here's their answer and the link to the video in their email response. Basically the same as what everyone here is saying. Will try this tonight.
"QuietDrive VorTech and Vectra built after 6/1/20, will have Mobius firmware preloaded. We do not recommend performing a firmware rollback unless you already have a large group of devices controlled via the ReefLink in EcoSmart Live or via the Neptune Apex. If you plan to control your device via the Neptune WXM module, you will need to perform this firmware downgrade procedure as well. The process can take up to 20 minutes and it's very important to be patient during this time. Do not unplug the controller for any reason, and leave the controller undisturbed for 20-30 minutes after the update completes.
The video below will demonstrate the firmware downgrade procedure.
Well, it did something. I'm just not sure what. It went through the firmware downgrade procedure and said it was successful.
However I still can't connect to my WXM Module.
In fact, none of MP40s can connect to the WXM Module anymore. Not the brand new ones. Not the QDs from a couple years ago. Not the super old white ones.
I updated the WXM Module. Tried the old unplug, plug everything on and off. Went through the reset modes for each pump. Tried to reconnect. Nope, nothing, nada.
So now I have 8 MP40s all operating independently. Pretty frustrating. Will reach out to ecotech.