Hi @danbeuckelaers
Don't know the camera but looking at the [https://www.manualslib.com/manual/2841925/Sony-Ilce-6500.html#manual|service manual] the door seems to be a part of the terminal holder assembly, but I may be wrong.
See manual p.2-7 (p.12 of 24 numbering) Item #167 part # X-2593-766-1
If it is the correct part, I can't find it online by searching for the part number, you may have better luck