Problem with RBS50 - does not connect to RBR50

I bought a used RBR50 + RBS50 combo a few months back. I was able to install RBR50 and with some trial and error the RBS50. However, the RBS50 kept on disconnecting from the RBR50. So I updated the firmware for both to V2.7.1.60. This seemed to do the trick and the mesh network was working in a very stable mode for the last many weeks. I elected to not update firmware any further.

Unfortunately, the RBSS50 was power cycled inadvertently and since then it has been a heap of trouble. The issue is as follows:

1. I power on the RBS50, the ring LED on the top flashes once (sometimes the top LED does not flash at all). The power LED at the back is green, but the ring LED on the top does not flash

2. I use the iPhone app to "Add a Satellitle" and follow the steps

3. I get the message "Satellite not found" along with a satellite LED color guide

The App showed the RBS50 as Diconnected. I figured that perhaps that was the issue, so I removed it from the network. And then went through "Add a satellite" in the App. Still no joy.

I have looked at various posts. One of them suggested that I connect my laptop to the RBS50 using an ethernet cable and see if I can get a DHCP IP from the RBS50. No luck with that.

I have tried to Reset the RBS50 multiple times. One one occassion I got the top ring LED to flash Green after reset. I have not found this documented anywhere.

The RBS50 unit is definitely powering on, but refuses to connect to the RBR50.

Would appreciate any help/suggestions.

P.S. I have NOT tried the tftp suggestion because the tftp client is being flagged by Chrome as being unsafe for download.