While not related to the chip in question, components can and do fail for no reason.Andy,
I realise this particular one under discussion was damaged by some mishap.
I have a QLG1 which was happily running for weeks, Problem was traced to the IC, there was a pulsed input but a constant output instead of pulsing. New chip ordered from a reputable supplier, fitted into a socket and GPS is now happy again.As Hans has said, can you be absolutely sure another fault was not rectified by the disturbance of the replacement? Did you test the IC after removal, or was it damaged by that unknown fault? It might just take a solder or wire remnant to short something before it drops never to be found. It sounds unlikely but much of our complex modern electronics run for years without failure.
Yes a few components do die but on the other hand I am amazed just how robust many are. ICs getting really hot due to being the wrong way round, complex SM ICs removed/replaced a number of times still working apparently normally.
73 Alan G4ZFQ