Just to update everyone who have been so helpful. The problem has finally been solved! It was a charger issue. The original battery was dead flat so the camera wouldn't switch on. Why it was showing 2/3 full just before it went flat is still a mystery. Will monitor for that. I went to buy a new battery to test with the original charger and that didn't work. Went to buy a new charger today, the new compact one... very much better the original brick! Now everything is fine. The US seller has refunded me part of the cost of the charger cos I bought the compact one instead of the old M8 one so all is good. Happy happy now.