Electric Skateboard Wheels Problem

The external shell of one of my hub motors has popped out during a ride (and the inner part got damaged from keep riding on it for few more meters until I stopped), and now it won’t get back…
I slide it back in (very easily, no tension or friction), and it simply slides out easily, with a gentle pull…

It also doesn’t go completely all the way in.. it’s like there’s a 1mm gap.

Any idea how to fix it?
without buying a new motor obviously… that’s the easy option.