> Currently Tesla just replaces the entire media unit when this happens, which is extremely expensive for them. In reality they only need to replace a tiny part instead of tossing entire boards.

Do you know that they toss the old media units? Are you sure they don't swap the entire media unit to simplify service procedures, and have have the old units inspected and refurbished (i.e. eMMC module replaced) for future repairs?

That sounds way more efficient than training all of the shop workers to diagnose and swap out individual parts of the media unit.