There are two bikes and two chargers?
Does the problem happen with both of them?
Does it happen with both chargers, regardless of which one is used on which bike?
If any of those is not true, what exactly happens with each bike and each charger, in each possible combination?
Are there supposed to be any lights on the chargers or the bikes that indicate charging mode? If so, what do you see them doing, vs what they should be doing?
With a voltmeter set to 200vdc, what voltage do you read between the various pins on the output of each charger, when the charger is plugged into just the wall AC source (into a plug you have verified is working using a lamp, etc), and turned on?
With a voltmeter set to 200vdc, what voltage do you read between the various pins on the charge port of each bike, without the charger plugged into it?
With a voltmeter set to 200vdc, what voltage do you read between the various pins on the charge port of each bike, with the charger plugged into it? (this may require opening up the panels/casing of the bike to reach the back of the connector)