This shows the normally-closed contact which was found to be fused. This contact carries the starter motor current, which is about 100-200A. The contact is rated at about 50A – a mistake by Socata.
This has happened several times in the 12 years I’ve had the plane. It takes about half an hour to change the relay. It’s not expensive…
But it’s a warning to those who went to the high power (original) Skytec high speed starters, which can draw up to 300A. The aircraft system may not be able to carry the current – even if the starter motor is certified for the engine and can thus be legally fitted under an STC. I went for the Skytec 149NL which draws a lot less current, but it still manages to fuse the contacts eventually.
There are options to fix this but the proper long term one would be, ahem, somewhat “visible” – a bigger relay.
More details here.
Presumably this happens when you start directly from a GPU….why not use the GPU to charge the battery for say 20 mins and then start?….FWiW I fried my ground power relay recently as well!
why not use the GPU to charge the battery for say 20 mins and then start?
See the link above for the circuit. The ground power relay disconnects the battery (totally) when the external power is connected.
That is on the GT and the non-GT recent models. There have been TBs made, early on, which did allow battery charging via the ground power socket.
It is highly desirable to install a battery charging connector somewhere, and carry one of those little specialised 28V chargers. To install the connector, you need its +ve wire protected by a fuse (close to the battery) in the standard way. Some pilots in the USA have gone public with such a mod, though some of them claim they filed a 337 (Major Alteration / field approval) for it 
