Help! Battery Full-Display shows empty-won't turn on!


New Member
I have a Pro-connect Kalkhoff Impluse 9 based on a 11ah 36v battery. A couple of days ago, I took my bike, turned on the pedelec, and came across the empty battery icon (as shown in attached image) despite the fact that my battery was full. (Battery is a 2014 battery but with more than 80 percent remained capacity and less than 20 cycles of charge out of 1100 cycles (according the factory-claimed capacity)).

Below is the list of what have done so far:

1- I took off the battery and let it charge to the balance point (green light) and put it back. Another time, I let it be on charger for few days, as some people had suggested for similar cases.
2- I checked all the connectors for loose connection.
3- I measured the voltage output of the battery and it was 42v which seems good.
4- I took the battery to a lab, and let it checked by a technician. All cells were fine with the right Amp and Volt. The only variation was 10 percent difference between some cells.
5- I tried to ride the bike several times and see if it understands my misery and come back with no reason!

All failed!

I am starving for any helpful advice, please!