I have found a solution so stupid it’s almost hilarious.
Step 1) Sit near the power adapter and plug the tablet in, make sure you start a Youtube video to maintain sanity.[br]
Step 2) Every time the tablet screen turns on, count to 5 in your head and plug it out, wait until screen darkens.[br]
Step 3) Repeat step 2 for about 15-20 minutes to build up enough charge to get into the custom OS loader thingy.[br]
Step 4) Enter custom OS loader thingy by pressing and holding power and down until a blueish green screen pops up, and press volume down to restart quick as this screen flashes too regardless if the charger is plugged in or not.[br]
Step 5) The very moment it boots up and asks for the pin (or if you don’t have a pin just the very moment it turns on), press the power button, and let it sit for about 4-5 hours. By this time it should gain enough charge for use, and make sure you never let the battery drop to 0%, no matter the cost.
This worked for me, maybe if someone else faces this issue and just needs a “quick” solution without removing the “non-removable battery” and replacing it with a better one, or changing a motherboard which I am the most suspicious about causing this issue. It charges perfectly now, just never. let. it. drop. to. 0%.