Orbi RBS750 disconnected from RBR750 and cannot reconnect

Orbi satellite RBS750 1 disconnected from the RBR750 after running like a top for 2 years. Internet speed was awesome everywhere in the house. 

• RBR750 is in the basement directly connected to the Verizon modem. RBS750 1 is on the first floor and within 20 feet of the RBR750. RBS 2 is on the second floor within 20 feet of RBS750 1.
• The Orbi Advanced/Administration/Attached Devices always indicated that the Backhaul Status of both RBS750's is "Good". And that all computers and about 30 other devices were spread pretty evenly between the RBR750 and the two RBS750's
• The RBR750, RBS750 1 and RBS750 2 are all on Firmware version V4.6.3.7_2.0.49.

Here is what I have done to get RBS750 1 back online:

1. I removed the disconnected RBS750 1 using the the Orbi BASIC/ADVANCED interface.

2. Did a factory reset of RBS750 1 intending to use the mobile app to "ADD SATELLITE."

    2a. RBS750 1 went from blinking amber LED and turned to green

    2b. Ring goes to blinking white and never to solid.

    2c. Trying to add the satellite while RBR750 is flashing white doesn't work.

3.  Moved RBS 1 to within 5 feet of the RBR750.

4. Disconnected RBR750 from Verizon GS-1100 modem and rebooted the RBR750

    4a. Rebooted the GS-1100 modem bringing in FIOS GB

    4b. Reconnected ethernet cable from FIOS modem to Orbi router

    4c. The RBR750 and RBS750 2 came right up.

5. Did another factory reset of the RBS750 1.

    5a. Blinking amber LED turned to green

    5b. Ring goes to blinking white and never to solid.

Repeated this several times confirming that I am insane by doing the same thing over and over expecting different results!  I've scoured the Orbi troubleshooting, the Orbi Community and the Internet for solutions, but never found one with this exact problem.  Don't want to blame this on hardware failure, but I'm out of ideas.

You will be greatly appreciated if you are able to offer a solution.