Bafang recently upgraded their magnet and it is all just one piece and held in place with a screw as shown in the photo above.
The new magnet requires T20 Security Torx bit to be installed with the screw. That being said this is a VERY unique bit style and not a common tool found in most toolboxes. Don't get discouraged, there is a way around this! Using only a small flathead screwdriver you should be able to screw and unscrew the T20 Security Torx bolt as shown in the attached photo and video provided below. With a little finesse from your flathead screwdriver this T20 Security Torx bolt can be installed without having to buy this special bit!
An additional youtube video is provided below for reference: https://youtu.be/doHYppOBbf4?t=97.