Hey !
I had the charging issue, bought a second transmitter in B stock and it would not work either but somehow I got them both working !
I openned them and cutted a small piece of the batteries cables to acces the wire. Then I forced the charge of the batteries with a 5V and 1 amp limit power supply.
I stopped when it started heating, and let it cool down for an hour. And now it charges well on the receiver.
This is not the safest fix but hey, if it works it ain't stupid, is it ?