I changed my chain on my Shimano Di2 Ultegra 8000 and I jumped on my bike to test out the gears and my Di2 was dead....dum,dum,dum,duuuuummmm. I took it to the bike shop and the mechanics have covid so they can't work on it. Here is what I tried. The plug on my bar end lights up red when I push the button and the flashing red and green works, but no shifts happen on the front or rear derailer.
.
1. Unplug the seatpost connection to the battery and reconnected it.
2. Check the junction box inside the frame to see if a wire came out...they didn't, and I reconnected all the wires to the junction box
3. Put the rear derailer into recovery mode, it did shift during recovery mode, but didn't do anything after that.
4. Charge the battery all the way up
5. Connected my laptop to eTube.

Any other suggestions to try?