There is a difference of opinions with regard to the button. Every single post I've read before I received my pocketbook was that there is no point in using the button. It is useless.
This was (officially) first mentioned in the
"washing up glove"-thread (although some users reported this already long ago) but be aware that Waldemar made this statement while he was referring to a 60x pocketbook!
In the youtube video thread he actually insists that for the 90x series you DO have to press the button. And highly official post by
Fork confirms this (posted last monday).
Without pressing the button, there is no way that I could open my 903. I tried for hours and it opened only after I pressed the button. However, be aware that the button does appear to do much but in fact it is essential.