Hi, is that door with the LED always red, also works with other batteries?
Very probably the cause of the problem is a malfunction of the charger, I fear that some resistor or capacitor of that port is broken ... it would be interesting to try to understand the problem and see to always solve it if one is practical and with some equipment to find and try to repair.
but since these loaders don't cost much today, perhaps it would be better to replace it with a new one.
Flydrone. You are correct, BUY a new loader (charger). There are screws under the bottom foot pads to disassemble charger. But then what?
The non-functioning charging door (station), let's name it 3, is the station at the opposite end from the USB power connection. With no batteries charging, the 3 station LED is extinguished and 1 an 2 stations LEDs are slow flashing green sequentially. If only the 3 station has a battery installed its LED remains extinguished. If a battery is installed in either stations 1 or 2 or both 1 and 2 then 3 station LED is solid red. 1 and 2 stations function normally; that is the highest voltage battery station flashes green and the standby station is solid amber. There are numerous other combinations of battery installation with different LED outcomes, but who cares. BUY a new charger.
I didn't mean "who cares" and buys a new charger!
but if you have the chance to take it apart, look for the problem and solve it, better not? ...
Now it is difficult to diagnose the problem here on the forum, without examining the charger with the proper equipment.
But if there's really nothing to do, you should buy a new one!
This is just what I think!
Flydrone, thanks for your responses and suggestions.
I will purchase a second DJI charger and will then be able to charge five (5) batteries sequentially.
Just surprised that a DJI product failed only after a little over one (1) year of light service.
I understand your disappointment about the dji product, but it would be interesting to try to repair it ... I only say this because I like electronics and sometimes I get to grips with these problems ... but it's not always easy.