All engines operating is the key. If you can make PDG (almost certainly) just follow the SID. Of course if it's a protracted SID you may not wish to do that as you're probably not continuing with the gear down.
As for using the override button. I would only do it OEI when obstacle limited. You don't know why it won't come up and you don't know what damage it will do if you force it. There are a few incidents of override leading to not getting the gear down at the other end!