The charger light is only on when the charger is connected to the junction and the battery is charging. Is your Di2 battery completely dead? I've had one bad internal battery since Shimano started offering the Bluetooth compatible system. It would take a charge and then die completely at times. This happened several times before it wouldn't take a charge at all.

I had a battery refuse to take a charge. It seemed like the same symptoms you are facing. I did a warranty claim and within 10 days, had a brand new battery at my door.

Contact Shimano. They'll take care of you.

The last time i had Di2 problems i took it to the LBS and they plugged a laptop in via the USB charger and showed a full diagnostic. I think the software is free and downloadable and the software was all very visual and easy to use.

Thanks, that is what I was looking for.

I just didn’t want to go fishing for my battery and the b junction if it was the charger that was the problem.

I forgot md the loose connection and the system charged up normally.

The normal charger can plug into a windows computer and run the free etube SW. That is also how you change a lot of settings and update. There is another connector box that does more indepth diagnostics which costs about $150. Do you remember which they used?

sorry, i don't remember.