MR60 — Nighthawk Mesh WiFi 6 Router

Netgear has set up a community forum specifically for the NightHawk MESH products. Most of the people who watch that forum are more likely to have experience with NH MESH products and know how to work it better than those of us who follow this router forum. Might be more likely to find someone who has a solution if the question is posted there:
https://community.netgear.com/t5/Nighthawk-Mesh-System/bd-p/en-home-nighthawk-mesh-system

Does the 1 MS not connect at all? If not, this means the MS didn't get update properly I presume. All MS should have same version of FW loaded. 

Try this to see if this works:

Manual MS FW update after MR was updated:
You need to update the MS before updating the MR. Keep this in mind for future updates.

What you need to do is factory reset the MS. Wire connect a PC to the 1st satellite📡. Already have the most current FW version files downloaded on to this PC.

Wire connect 1 PC to the back of the MS. Factory reset the MS, wait about 5 minutes. The PC will get a IP address from the satellite📡. The RBS will be 192.168.1.250. Use this IP address in a web browser to log in to the satellites web page. Log in as admin and password. Use the satellites 📡 web page FW update feature to select the FW update file that was unpacked from the .zip file. Then factory reset and then re-sync the satellites 📡 to the MR.

Please use this link to the main forum product list to review and choose where to make your posts. 
https://community.netgear.com/t5/NETGEAR-Forum/ct-p/en-netgear

Thank you.