If you replaced the LED strips but didn't replace the power supply board and still had the identical problem, it's either:

● The power supply board, with the most likely problem being the electrolytic capacitors as I stated in post number 2.*

Or

● Bad cables between the LED strips and the power supply board, an unlikely failure.

* The argument that it can't be the power supply because one side flashed and one side doesn't assumes that the power supply is connected in parallel to both strips. Looking at the board however suggests there may be separate sections for each strip.

Thanks Jon…late last night I piddled with it more. Remember, the new unit (module with two LED panels) acted the same way and on the same side. I kept fiddling with the 4 wire connector that couples to the new module, and I would almost swear it’s an erratic connection on one of the 120v wires feeding the new module. I could make it stay lit steady for a bit and my last attempt for the night it was still working fine. Couple times when I opened the doors that same LED panel slightly flickered and then stayed lit…
More tomorrow…

 

Here’s the tech sheet I finally found:

 

If you replaced the LED strips but didn't replace the power supply board and still had the identical problem, it's either:

● The power supply board, with the most likely problem being the electrolytic capacitors as I stated in post number 2.*

Or

● Bad cables between the LED strips and the power supply board, an unlikely failure.

* The argument that it can't be the power supply because one side flashed and one side doesn't assumes that the power supply is connected in parallel to both strips. Looking at the board however suggests there may be separate sections for each strip.

One more thing from last night…
I was running some DC to the LED panels to see if they were still lighting ok (I had separated them from the module.) My wall wart supply was 12v but I believe it was putting out more like 16-17v…I would briefly touch the input power pads and the lights all lit brightly. BUT, it seemed to take quite a bit of finesse to get the input pads to take the power. I tried to desolder the wires from one panel earlier and it was near impossible…like maybe some crap China soldering. I’m thinking now of pulling the new module back out of the fridge and really reworking those solder connections. (Can’t experiment with the old module/panels now, since late last night I slipped up and somehow applied 120v to the wrong wires on the module and got that dreaded loud SNAP! and spark… And that was using my dim bulb tester too! )

 

…like maybe some crap China soldering.

Given the application it's almost certainly lead-free solder and that can require a higher temperature than typical lead solder.

 

Are all those lights intended to come on when a door opens? If so, I'd be checking the door switch and its connections.

 

Are all those lights intended to come on when a door opens? If so, I'd be checking the door switch and its connections.

Hard to see how that could cause only 1 side to flicker.

 

So…I’ve been consumed with so many other fires to put out that I’ve not been able to get back to this yet…and rethinking my steps again…
Can anyone tell more with the tech sheets I attached earlier?
I can’t seem to find any other part that would affect it—since the light panel has a module within it that houses a power supply and another board I’d imagine is a LED drivers circuit. It has 110v feeding it and I believe it has feeds that run to the bottom drawer and freezer unit. Those lights do not have any problems. The first part I ordered was just two circuit boards with the LEDs on each, and connected together. Then the assembly plugs into the harness on the cabinet top. I didn’t realize mine was different—had the two LED boards, but also had the circuitry between them. So I ordered another part…this time the LED boards connected to the circuit module. Surely this would fix it, right? Nope. Very same problem. How could that be?? Although it seems it has less erratic flashing or they just quit for a period.
I’ve exercised the two door switches and I can’t see any kind of issue with them. But, the harnessing on the cabinet ceiling I’m wondering about—maneuvering them around in different ways it’s not a clear cause, but it’s all I have at this moment…

 

Here are a couple more pics:first one is the replacement LED panels. Second one shows the assembly with the power and driver boards in a box between the panels.

 

The first picture in post #28 shows that the 2 LED panels are connected in series but the picture in post #11 shows that each panel is connected to the driver board.I assume that post #11 is what you have. Did you try swapping over the two pannels as suggested in post #12 ? One other thing that you could try is to monitor the voltage between the wires at the panel when the panel is is working and when it is not working. If the voltage goes down when it is not working the the fault is on the driver. If the voltage goes up when it is not working then the fault is the panel. The is because the panels will be supplied from a constant current source. (NOT a constant voltage.) Your test with supplying them from a constant voltage source had the potential to destoy them.
Les

 

The first picture in post #28 shows that the 2 LED panels are connected in series but the picture in post #11 shows that each panel is connected to the driver board.I assume that post #11 is what you have. Did you try swapping over the two pannels as suggested in post #12 ? One other thing that you could try is to monitor the voltage between the wires at the panel when the panel is is working and when it is not working. If the voltage goes down when it is not working the the fault is on the driver. If the voltage goes up when it is not working then the fault is the panel. The is because the panels will be supplied from a constant current source. (NOT a constant voltage.) Your test with supplying them from a constant voltage source had the potential to destoy them.
Les

Thanks Les…
Post 11 pic is correct…post 28 I wasn’t clear—the left pic showed what I initially ordered, which was for a version that had the power and driver boards elsewhere, and only the lights were connected together to plug into the harness at the cabinet top. The right pic was my model—has the two panels separate and wired into the power and driver boards box.
I believe I swapped the panels and problem remained on that same side. I also did a test of applying a quick voltage to each light panel and they worked fine.
I’ve gotten away from this one for a bit and just last night was revisiting it again The flickering is still annoying and I’m still a little nervous messing with it—I HATE that SNAP/FLASH/SPARK when it happens; makes my heart nearly jump out of my chest! (I DO try to be careful but occasionally it happens) Looking back I recall I mixed up my power in the small harness in cabinet top—I ASSUMED the bigger gauge wires were AC…I know better now…
I’m still hung up on thinking it’s a wiring problem in/near the plug harness, and want to dig a little deeper with that, and also the testing you suggest…
I’ll look at it again today.