Hi,
Yes this is a really tricky part to get back on.
I’ve had success by holding it at angle and using a flat screwdriver to gently press it back on to the stud, then rotating the other end very gently back to where it sits at the end of the Taptic Engine.
Be careful not to force the button end onto the stud, you can easily damage the round connector and then it won’t grip.
Bit of a fiddle but it can be done.
Hope this helps