Replacing the plastic body frame on the Fenix 5 Plus?

Hello, I bought a used Garmin Fenix 5 Plus and one button (DOWN) is bad. I can get a replacement body (just the middle plastic one, with buttons) from AliExpress for a low price. Have anyone replaced this part before, is it easy? And does anyone know for sure if the 5 Plus is identical to the 5 in terms of physical measurements?