I used the Shimano E-tube iPad app yesterday with my Di2 equipped bike. The bike has the updated battery (BT-DN110) and updated D-fly (EW-WU101). I was able to BLE connect the app to the bike with no problem, and it recognized correctly all the appropriate Di2 components on my bike. So far so good.
The app showed that the firmware for all the components was up to date, except for the battery. It asked if I wanted to update the battery firmware and I said yes.
It downloaded the firmware and got to 100% on the progress bar, and then stopped. It wasn't clear to me if 100% was 100% downloaded but not yet installed, or 100% done with the installation. It warned me of disconnecting during the installation so I waited... And waited. And waited. After I couple of hours, I concluded it had to have hung; no way it could legitimately take a couple of hours to install firmware for a battery.
So I killed the app.
Now the bike doesn't shift anymore. Nothing about Di2 works. I plugged in the charger, the charger doesn't show it's charging. I press the button on the junction box, no lights.
I restarted the e-Tube app and BLE connected to the bike. It detected a failed install of the battery firmware and said it needed to download the firmware and overwrite the battery firmware currently installed.
OK, sure. Now the screen said, The firmware is currently being overwritten. Do not disconnect until overwriting is complete. The progress bar goes to 100% and stays stuck there. 22 hours later, same thing.
I don't own a PC (only Macs now) so can't install the firmware from the PC via the DI2 cable. And the Di2 is still dead.
I took the bike to the shop to get them to manually install the battery firmware. They couldn't get it to install even with a wired connection. The battery was nonresponsive. They replaced the battery with a new one and are sending the old one back to Shimano under warranty.
Now it works fine.
When I got home, I was able to connect the E-tube app to the bike again. It said there was an update to the battery firmware, did I want to install? This time I said no