Having read the limited instructions for this watch, it does not seem as though there are many options available!
If you haven't already done so, try pressing A again.
If nothing happens, press B
It could be that the watch has simply stopped because it needs re-winding (it depends on how long it had been running when you got it.
To wind the watch swing it gently from side to side for a few minutes. ( some makers say swing it 200-300 times!).
If you still have no joy, then contact the makers help line; go to
http://www.raymond-weil.com/EN/Swiss-Watch-Company/After-Sale-Service.html to find your nearest service center.