I have had 4 Samsung phones over the years and each one has unexpectedly died and been unrecoverable. The latest one is an A5 prior to that a Galaxy Note 4 and prior to that 2 earlier samsung models. Apart from the inconvenience when a phone just dies even if you have had backups running, it is putting me off buying another Samsung phone. Is it unreasonable to expect a phone to keep working for a number of years? These are expensive items. Is obsolescence built in? Not a happy bunny.