A chap brought a DA40 with 2 x GNS430 into the place I work. Both 430s didn't function. Lots of shoulder shrugging as to what had happened. Actually he tried to replace both batteries himself and had not been successful. Garmin charged their flat repair fee. Expensive mistake. I don't know how different a 750 is to a 430, but it may be worth finding out how much the professionals charge to avoid a much greater bill ... Pete