[Galaxy Note Pro 12.2 Q&A, Help & Troubleshooting] Beut:
First, pressing the battery connector help your tablet to boot is a confirmation of cracked battery connector solders. 90% flickering problem is from cracked battery connector. 10% is bad battery. You should fix the battery connector first as it's major defect seen in many Samsung tablets. Re solder is simple, apply flux, then heat these pins and add more solders as possible to secure these pins. Even new main board, this connector will crack just after 3 or 4 months depending how you use your tablet, especially with who using it on their laps. The main board sits on a flexible LCD and only 3 screws to hold it to the frame at 2 speakers. You don't need to remove the main board, just disconnect your battery and re solder the connector from the top.

Be careful as this connector is very close to other components. Trust me, this re work will fix this problem as I have seen in some cases, battery jumps up from 8% to 45% after the re work, other cases pressing the battery connector help the tablet to boot or stop flickering.

This person applied the fix and succeed.

http://forums.androidcentral.com/sa...screen-flickering-problems-3.html#post4473418

I have the Note Pro 12.2 and I had this same screen flickering issue. It would start to flicker at first around the 38% mark. I did research online and found this thread and many others. I tried the software fixes like the enabling of Developer Mode and screen brightness and other tries, but to no avail. When I pressed on the back of the tablet, the screen flickering would stop but then shortly return. So I saw the fix of trying to raise the motherboard which worked for about 2 weeks, then the screen flickering did return. It would then start to flicker around the 58% battery level mark and when it got down to around 26%, the tablet would shut down. When I plugged it in, it would show battery level of 0%, then quickly jump back up to the 26% mark when it shut itself down. So then by this time, I saw more of this thread and now was shown the soldering of the battery connectors. I had soldering equipment, but it was too large for this repair as these 6 pins are very close together. So I went to the hobby shop and purchased new equipment for about $30 with a smaller pin to be able to do this. Now, I am not an electronics guy and my past experience was replacing two bad capacitors on my Plasma TV when it went bad. That was the extent of my experience to date. So I opened up the back of my tablet and soldered the 6 pins again and the screen flickering has not returned. I am on my 5th battery cycle from 100% all the way down to 2% and the screen flickering and shutting itself down has not returned. Some people have said an electronics guy will do this for you for around $30. Well, I spent the $30 and did it myself. I want to thank the people for posting the solutions here as the soldering worked for me.

And from this post, a confirmation that repair center will do the same thing to fix flickering , auto reboot, auto shut down.....etc...all problems caused by cracked battery connector ( Connector Header ):

http://xdaforums.com/showpost.php?p=58943998&postcount=74