GPSmap 62s does not start up any more

Dear all,

During a trip, I had my GPSmap 62s tracking the route as always. It seemed to be working fine, and I switched it off when I returned home. When I tried to turn it on again, I saw the message "Loading waypounts, tracks and routes..." and then the screen faded to a blank screen. Changing batteries to fresh ones does not help. This also happens when I try to connect it to my computer with a USB cable. Does anybody have an idea what I can do?

Thanks in advance!