Kukirin G4 not charging correctly light switching between red and green.

I just got the scooter today. When I unboxed it, I noticed that the charging port dust cap was off. I’m not sure if this is related to the charging issue.

When I plug in the scooter, the charger will sometimes show red, indicating that it is charging. However, after about 5–10 minutes, the charger starts repeatedly switching between red and green every couple of seconds. The scooter is only around 6 bars charged when this happens, so it is not fully charged.

This has happened multiple times. I also noticed that on one occasion the charging plug was not fully seated in the port and one side was slightly pulled out. I repositioned the scooter so the charging cable would not be under tension, and I made sure the plug was fully inserted. I also layed the brick flat.

The charger brick also becomes fairly hot while charging.

The scooter itself powers on normally, and the motor works properly. The issue appears to be specifically with the charging behavior.
I would like to know whether this behavior is normal or if the charger, charging port, or scooter may be defective.