Orbi - Can't connect or update satellite-2 firmware - Router and Sat-1 versus Sat-2 version issue

I have RBR50 router plus two RBS50 satellites. I have been running with only 1 satellite for about a year and now need to add the 2nd satellite. I tried to add the satellite but it won't connect. Magenta satellite ring when I tied to sync and admin info says backhaul "Poor" and connection type 5G. I've tried to connect in troubleshooting a few feet from the router to eliminate distance issue. After troubleshooting I realized the router and sat-1 were on firmware v2.21.210 and the older "new" satellite was still at oringinal v1.20.6

 

I tried to do manual update. I downloaded the current firmware RBS50-v2.21.210.img from Netgear site but each time I try to update I get message "This firmware file is incorrect! Please get the firmware file again and make sure it is the correct firmware for this product."

I have tried this many times with no success. Any suggestions?

I am using mac osx 10.12.6

Kind regards,

Mark