I have many lithium battery chargers and all of them put put a steady open circuit DC voltage consistent with their target voltage, 8.4, 12,6, 42.0, 54.6 or 58.4. That's the basic approach to charging. There may be some proprietary systems that come in with pulsed DC, but you're not going to see the chinese bike makers trying to copy it.
Have you removed the battery from the bike and taken a look at the contacts? Make sure they're clean and there's no debris that may be doing something weird. Have you tried to charge the battery when it's not on the bike?
Other than that, most diagnosis involves opening the battery, and that makes it harder to make a warranty claim, so all you can do is wait.