The charging door of this Think has never really worked - even if closed tightly it would get back to being a bit open after a short drive.
After some troubleshooting it turned out that the charging door has a magnet that is supposed to attract the charging door to the body of the car where there is another magnet. A simple test with a circular magnet showed that the magnet in the car body and the charging door were oriented with their poles in such a way as to repulse each other!
Some prying got the rubber cup containing the magnet from the body of the car and then it was easy to pry out the magnet rotate it 180 degrees and then glue it in the cup with some instant glue.
Now the charging door sits well and tight to the body of the car.
Here are some photos I took during the process.
