sounds like the same issue for us....I've reported the following and am waiting a reply:
2018 Sondor thin
LCD (B2222 36V)/power problem
My husband and I have 2 of these bikes and have about 180 miles on each with no issues until now. My battery is fully charged but when the bike powers up the battery only shows 1 bar which last only 2-3 minutes. We swapped batteries and mine works perfect in the other bike; but my bike has the same issue with the other battery. Thus, we have eliminated my battery being the issue. We have done the same thing with the controller with the same results. We then switched the LCD unit and mine did NOT work on my husbands bike. We are now believing my LCD is the issue. Please note: my LCD presents all information correctly (average speed, odometer, power assist level, etc.) Is there a way to reset my LCD and if not, how do we purchase a new one quickly? We are grateful for any help....thank you.