Orbi RBR50 satellite factory reset doesn't work

Try something from this list:

Bricked Orbi Recovery:
https://www.snbforums.com/threads/custom-firmware-build-for-orbi-rbk50-rbk53-rbr50-rbs50-v-9-2-5-1-18sf-hw-v-9-2-5-1-18-1sf-hw.64414/page-3#post-590839
https://community.netgear.com/t5/Orbi/Is-my-13-month-old-RBR50-bricked/td-p/2009904/jump-to/first-unread-message
https://community.netgear.com/t5/Orbi-Wi-Fi-5-AC-and-Orbi-with/ORBI-RBR50v2-bricked-Solved/m-p/2338097#M145450

ttps://kb.netgear.com/000059634/How-to-upload-firmware-to-a-NETGEAR-router-using-Windows-TFTP
Need to press the reset button for 30 seconds then release, then it send to PUT the command and upload the FW. 
Make sure you enable tftp: https://www.thewindowsclub.com/enable-tftp-windows-10
Video walk through using a tftp client. Use the built in one for windows 10 though. the video is more of an example of how its done:
https://www.youtube.com/watch?v=hXhMgQS5k1o
https://www.youtube.com/watch?v=R9DLrLQrpaw
I had a problem on a Windows 10 PC where this didn't work to use TFTP, so I switched to a Windows 7 PC and the TFTP worked.
Mac TFTP: https://www.petenetlive.com/KB/Article/0001247

Try nmrpflash:
https://github.com/jclehner/nmrpflash
https://community.netgear.com/t5/Nighthawk-WiFi-Routers/R8000P-V1-4-1-50-Update-workaround/m-p/2248802/highlight/true#M219856
https://community.netgear.com/t5/Orbi/Orbi-RBR50-seems-stuck-in-boot-loop/m-p/2010016/highlight/true#M107358
https://community.netgear.com/t5/Orbi/Is-my-13-month-old-RBR50-bricked/m-p/2011090/highlight/true#M107511

If any of this fails, you'll need to replace the RBS. 

Good Luck.