bester

Okay, I found it.

After removing the mechanism, I turned it on and noticed that it only worked if I pushed the motor towards the battery. Once I removed the spring I noticed that one of the two metal strips connecting the motor to the board was split right where there is a slight bend. I applied a little bit of solder to repair the connection and it is working again.

I have the same issue. It worked fine a few times and then quit. The display works fine, too.

I accidentally started it while taking it apart. When I was loosening the base, it started to work again. There's something applying enough pressure to the mechanism to stop it whenever it is pushed into the handle.

With the base re-installed, the toothbrush stops again. It works whenever I push the assembly down. I'm suspecting that the blue ring at the top may have something to do with it.

I found that I had to turn it counter-clockwise. It only tightened when I turned it clockwise.

Instructions for replacing the seal are here: Remplacement des bandes adhésives fixant l'écran d'un iPhone

I just had the same experience. The blue backing would not separate from the adhesive.

I tried a new tactic: Remove the ping backing and apply to the case, and then remove the blue backing. No go. It stuck to the blue backing more than it did to the case.

I should have just left the remains of the old strips in place. Instead, I just installed the battery without the adhesive. I hope that’s good enough.