Sadly I can't help you. But mine actually broke a few months ago and the mechanic just swapped it out in 10minutes. I have no idea how he did it but he told me there was a way on the inside. Still clueless on what he meant but I'm happy that its an easy fix.
Hi all, A200 AMG SPORT, thanks for replying and having read other post & watched lots of video’s I was determined to open the petrol ⛽ flap. having Stripped half the boot paneling and found nothing to be able to open the flap i took to vigorously tapping the flap for approximately 10 minutes , it got to the stage that I wasn’t tapping I was thumping it, 😬. and guess what it miraculously it OPENED. 😳. Did I loose my temper YES.
After playing with the locking mechanism for some time using WD40 it was apparent it wasn’t going to work, ☹ so I removed it and have ordered a new one. There’s more ,,,, on removing it ( which was very easy ) looking in the hole 👀 I could see a rubber grommet, with a long thin screwdriver I pushed it through, looking in the boot it had come through the black lino soundproofing which is glued to to the inside of the boot 😊. Hope some of the above will help. 👍.