Samsung Frame TV 2022 stuck in boot loop

I have a Samsung Frame TV 2022 (model QN75LS03AAFXZA) that is stuck in a boot loop. The backlight comes on, "The Frame" title screen shows, and I can hear clicking from the One Connect Box.

I've opened the screen to try and diagnose the issue, disconnecting various components to see if they have any effect on the boot loop. I've disconnected the speakers, wifi module, power button/IR receiver, left display driver board, right display driver board, both left and right driver boards at the same time, and the primary ribbon cable coming from the main board to the middle driver board.

The only change in the boot cycle is when the primary ribbon cable is disconnected, in which case the One Connect Box will click one additional time during the boot process. When the ribbon is connected the process goes:

"click" > 10sec > "The Frame" title for 5s > blank screen again 5s > "click" > 10s > "click" twice quickly > start again.

With the ribbon disconnected the boot process goes:

"click" > 10sec > "click" > 10s > "click" > 10s > "click" twice quickly > start again.

The mainboard is model is BN94-16865Z

The driver board models are ST7461D02-6-XR-1, ST7461D02-6-XM-1, and ST7461D02-6-XL-1.

I don't see any physical issues with the power board, though I don't have multimeter to test any of the components on it. The backlight appears to be working correctly however since the title screen displays.

One thing I have not tested yet is taping off pins on the primary ribbon cable, which I may still try. Given the behavior when the cable is disconnected however I suspect the issue is the mainboard. I'm looking for a sanity check before ordering a replacement mainboard. Given the behavior, does this diagnosis seem correct?