So I have a galaxy note pro 12.2 and it does not take any charge I shows it charges but it does not gain anything. I just bought a new battery for it and it is the same problem.
Install Ampere . Then you can measure the amount of current the tablet is using itself, then the amount drawn to charge the battery. If the amount drawn to charge is the same as the amount used, there's nothing left to charge the battery. That would indicate a bad battery or a bad charging circuit in the tablet.
Considering that the tab is almost 5 years old, there may not be any good batteries left for it. (Most of the ones you can find have been sitting on the shelf unused since the beginning of 2014.) You can try leaving it connected to the charger 24/7 until it shows signs of charging, charge it to 100%, use it until it tell you to charge it again - repeat the cycle twice more and see if that reconditions it. but if it just doesn't take any charge at all, it's either a bad battery or a problem with the charger circuit.