I just bought the Metz 48 af-1 digital flashgun less than a week ago. It work just fine for about two hours, then the screen read "er" where "zoom" used to be. Now when I turn it on the select + light just flashes red and the screen goes blank. I need this flash to work, I'm pretty booked up and need a reliable flash. Is this sort of thing common? Does anyone know what is wrong and most importantly, how do I fix it? thanks in advance.