Is the battery's cable connected completely?
When I replaced my seat tube battery (after 5 years!), I didn't click the cable in all the way. There's an initial click feel/sound, but it's not in all the way. Pressing a bit harder, it clicks once more!
The small plastic Di2 tool, with a pry hook on one end and a tube shaped push fitting on the other end, makes disconnecting and reconnecting the cables safer and more reliable.
I only figured out what was wrong after trying a bunch of other things. Grrr. I should have known.
EDIT-- sorry, I thought you had no responses at all. I see you are getting some lights. Still, it could a loose connection on one of the cables you unplugged and replugged.
Last edited by rm -rf; 05-11-21 at 07:01 PM.