Cradle
I assume you mean the cover on the cradle, not sure why you have removed it, I just flip up one end, when attaching headphones. Maybe someone on here as actually removed the whole thing and will be able to tell you how to replace, would have thought it would go back, have you bust it?
I have not got access to the unit at the mo but from memory I am sure the rubber cover is secured by a small screw in the centre, If you have ripped it then I would presume that you could get a replacement.
If you don’t have any luck give Garmin a bell or speak to the shop where you got it, hope you get sorted as I am enjoying mine.