I’ve got an original battery that was left for some time drained and as may be expected it lost in a way the ability to charge. “In a way” means that with controller bypass and my old trustful HP PSU I noticed the battery itself seemed alive and I managed to charge it until voltage got back at 12.5v in the cells and it shows it’s charged at about 50%. However, and this is the sad note, system doesn’t charge it further (although all battery data are there cycles, capacity which is very good and so on) nor gets powered by the battery.
It seems from my limited battery technology knowledge that the controller got in the red light state and holds power flow in both directions. Anybody has ever looked deeper into Apple batteries architecture and knows of a way to reset the controller, if ever possible ?