Meat Plow Inscribed thus:
I've never had to or been called to repair these things. Last damaged
Ethernet device I encountered was a 24 port Cisco Catalyst series
managed 10/100 switch that had suffered a proximity lightning strike
knocking out several ports. It was replaced, no way I would tackle a
repair.
Generally speaking they aren't worth the time to take the box apart let
alone fault finding on them. But as part of a larger job it can become
worth the effort to do so ! It also marks you out as someone who can
be trusted to do a job properly rather than box shift or bodge. In any
case its all part of a continuous learning process.