Glad they did that. Same happened to me - a 3 yr old PilotIII would just switch itself off after 5 mins and sometimes would not come on at all. They replaced it free after sending it in for examination.
I had a few email discussion with one of their techies about it. The problem seems to come from putting in rechargeable batteries of a certain kind. Which I had done. They have a characteristic that fries a power management circuit. It is a well known problem apparently.
I'd only ever used Duracells in mine - don't have any rechargables. And it had led a cossetted life, that's why I was tad annoyed when it died so young...
SSD