Do you remember if it was 2 of the matched leads that were reversed? They definitely have some issues, but mine are on the 2 matched leads that have one battery and one rc together. I still haven't taken it apart to check it out because I love the DJI charging station that I ended up with also. So I can still charge all 7 batteries at once.I bought this same charger and 2 of the 3 leads would not charge a battery. Checked it with a volt meter and found the polarity was reversed. Poor quality control!
Fortunately I purchased on Amazon, so no problem exchanging it for another. The replacement has been working just fine for several months now. I would recommend it with the caveat that buyer beware that there may be quality control issues letting bad units escape into the marketplace. Otherwise it's a nice little charger.