turn it on first, mine only seems to charge if it is on, or in sleep mode, mines does nowts if it is fully turned off.
Would be up the creek if the battery was flat as wouldn't be able to do either.
I christened my 590 last weekend. 903 miles down and around the Loire. I'm really pleased with it. Expensive bit of kit that does lots of stuff that I don't need (music, smart phone weather etc) but the screen and the way it changes from heading up to north up and view route at a touch of the screen is very slick and smooth