Refurbishing is a completely different “art” compared to regular repair, and unfortunately, there aren’t may refurbishers who patrol this forum. You could check out the iFixit Pro Forum (pro.ifixit.com) and also join the refurbishing related groups on Facebook or Reddit. Hopefully there you will find the info you need.
Just don’t forget to come back here once you have the knowledge so that you can share with the rest of the community.