You can verify this cracked battery connector by many ways:
1- When the screen is flickering: press on the back rear cover, near the center ( location of battery connector ), the problem will go away at that moment.
2-Slap on the back cover hard with your hand: your tablet will shut down immediately if it has a badly loose or cracked battery connector. This method won't work if the crack is not really bad. A bad one when you can move or lift it slightly with a screw driver or any other tools.
3- Inspect it under magnified glass or microscope, this one requires experiences or just simply push it slightly to right or left to see if it's moving, a bad one can be lifted easily.
The video on Youtube is no longer available because the poster may realize lifting the motherboard is only temporary close the gaps of cracked solders from battery connector.
This rework only takes under 5 minutes for who knows how to solder. Any repair shop can help you with little charge, all you need to do is to remove the back cover and ask someone to do the rework, no need the experience how to repair a Samsung tablet, even the experienced ones may not know how to fix this flickering problem.
When doing rework, add more solders as much as possible to secure the connector to mainboard, the reason: nothing to hold the mainboard along with the battery. The mainboard has only 3 screws to hold it at two speakers and it sit on top of the LCD, use your finger to push the mainboard at its' battery connector, you'll see it moves up and down easily. No matter how old your tablet is, sooner or later the battery connector will crack, especially if you have a habit to use it on your lap. To avoid this problem, I recommend a hard case cover should be used to minimize the movement of mainboard as it sits mainly on top of a flexible and fragile LCD assembly.