Just a thin KAPTON link cable!

My Problem

No communication anymore between the HDD and the Main Board (CPU), while all OK with an external SDD on the external USB socket of the MacBook Pro.

My Fix

Direct & easy internal replacement.

A quarter of an hour operation.

My Advice

Took advantage of the repair to replace the 500GB HDD by a 1TB Samsung 840 EVO.

All went softly and Time Machine did the rest.

Thanks FixIt!

Thanks also to Apple's Genius Bar to have found that an internal connection wasn't working: