RBR750 Boot Loop - White Light Flashes Then Goes Dark, TFTP Recovery Failing

RBR750 Boot Loop - White Light Flashes Then Goes Dark, TFTP Recovery Failing

Device: Orbi RBR750 (Serial: 6661037RA0169, Firmware was V7.x, Purchased April 2020)

Problem: Router powers on, white light flashes for about 1 minute then all lights go off completely. Unit is in a permanent boot loop and cannot complete startup.

What I've tried:

• Factory reset (holding reset button during white flash window)
• TFTP firmware recovery via ethernet from Mac Studio — file RBR750-V7.2.8.5.chk — unit responds to ping at 192.168.1.3 but TFTP times out with "didn't receive answer from remote"
• Accessed 192.168.1.1 but it routes to upstream Netgear router not Orbi
• Tried orbilogin.com, orbilogin.local, 10.168.168.1, 192.168.1.3 — none load admin page
• Mac internet sharing enabled (WiFi to Ethernet) to provide internet source to Orbi during recovery attempt

Current setup during recovery attempt:

• Mac Studio ethernet → Orbi yellow WAN port
• Mac on WiFi via backup Netgear R7000
• Mac ethernet set to static IP 192.168.1.2
• Orbi responds to ping consistently but web interface unreachable

Question: Is there a specific TFTP timing window or alternate recovery method for RBR750 that could help? Any known firmware corruption fix for this boot loop pattern?