I’d seen another group of postings suggesting that a good number of folks had had trouble with the G9 roughly 12-18months after purchase – and that in many cases it was found to be a couple of tiny internal screws that work loose, then roam around the inside of the case until they eventually cause an internal fuse to blow. I could well believe this to be the cause – the vibration of riding over rough tracks while holding the G9 could well be the final straw for this sort of fault. Looking at the camera back, it’s very easy to remove the back cover, (with a tiny screwdriver!) but no screws seemed obviously loose inside.
So I’m totally stumped now – my best guess is a catastrophic motherboard failure, and that’s beyond me for repair – or even investigation.
So it probably needs a return to Canon for repair now (sadly it’s not covered under the CPS scheme, despite the number of pros that use them) but it seems they have a standard price for all G9 repairs – £100 – whatever the problem. As they’re currently going for c£50 (broken) and £200-£300 (working) on Ebay, I guess it’s still worth repairing…