[Galaxy Note Pro 12.2 Q&A, Help & Troubleshooting] mikey5:
Just wanted to post to say that the plastic shim is working for me. I have had flickering issues really badly. Literally any time my power drops below 80%, the flickering begins, and it becomes unbearable by the time I reach the 50% - 60% mark. So, basically, I have to work with my tablet plugged in nearly all of the time. Also, certain activities set off the flickering more than others. The flickering is especially bad when I multitask with S Note on half the screen and a PDF file on the other half (which I have to do quite often).

Last week I pulled off the back cover and re-seated the cables around the battery. That didn't do anything for me. The flickering was the same as before.

Earlier today I tried the plastic shim trick and so far, it's working flawlessly! I'm shocked. I'm at 45% and am multitasking with four apps -- three large PDF files + S Note -- and I have not seen a single flicker. I use this device heavily every single day and know exactly when the flickering will begin and what will trigger it. This is definitely a big change.

The video from upthread is no longer working, so I had to make some guesses and assumptions about how the shim trick would work. Here's what I did.

1. I powered down the tablet.

2. I removed back cover.

3. I placed the tablet with glass down in a landscape orientation. The slot for the S Pen was on the left. The long edge closest to the batteries was closest to me.

4. I got the plastic from an old CD jewel case with a clear plastic cover. I broke the plastic cover into pieces and took two of them -- a larger piece and a smaller piece -- for this project. The smaller piece is the piece of plastic that I permanently put under the motherboard. The smaller piece was completely flat and had about the same dimensions as the fingernail on my first/pointer finger. The larger piece of plastic is something I used as a lever temporarily to prop up the motherboard while I inserted the smaller piece. The dimensions of the larger piece are not very important -- I just needed something that was longer than it was wide that I could use as a lever to prop up the motherboard.

5. The bottom left corner of the motherboard was exposed. I inserted the shorter edge of the larger piece of plastic under that corner of the motherboard. I pushed down on the other shorter edge of that larger piece of plastic in a lever motion, so as to lift the motherboard very slightly. With the motherboard corner held up by the larger piece of plastic, I slipped the smaller piece under the motherboard. This was not easy, as the motherboard was fairly secure, and there was not much room to work with. But I got the little piece of plastic under the board. Then I removed the larger piece of plastic (the lever) and threw it away.

6. I reattached the back cover and rebooted.

So far, so good. I'll report back if I experience any problems.

I see above that soldering may also fix the problem and may be a more direct way of fixing the problem. I wanted to try this before trying the soldering idea. I may try soldering if the flickering comes back.

Edit: Three days later, and still not a single flicker.