New battery failure is very rare, so if the watch fails to start with a new battery, it may be that the watch has stopped working for some other reason and you may
need to take it to a watch mender. However, there are a couple of things you can try first:
a) The obvious one is to check that the winder (crown) is pushed fully home.
b) If so, then has the watch been left standing with an old battery inside it for a long period of time? Sometimes it can be difficult to get the movement working
again if it has been stopped for a while. Placing the watch in a warm place (like an airing cupboard) can sometimes "loosen" things up sufficiently to get the
mechanism working again. We have fitted several new batteries to watches which have started for a while then stopped. Leaving them in a warm airing cupboard over night has actually
got them going again. You can also try moving the hands and tapping the watch gently to see if that will encourage it to start moving.
It is always best to replace
a battery in a watch as soon as the watch stops working.