Does anyone know what 'newly overhauled' actually means?
Amazon have them and it is advertised with a 12 month guarantee so it must be similar to factory reconditioned
Yes. But what exactly do they recondition when it's in the factory? I have an image of Garmin drones sweeping up discarded and broken 550's from all around and taking them off to be polished and repaired........
With Garmin they will have the same appearance as a new unit and tested to the same level as new ones. They are giving them the same guarantee is new, retail units. Most likely they will be units never sold to customers, either held in the factory after failing the test process or recalled from the distribution network once a fault became apparent. I used to run a unit for Xerox that did this sort of thing for their self-made printed circuit boards. You get a couple of failures in the field so recall the whole batch of maybe 10,000 units to be reworked. All because someone didn't clean a solder paste screen very well, giving you a few dry joints that escaped the test process.