if you look at the whole length of the crack, you might see a wide spot where it hit something. You might need to take a flashlight from ALL angles to see it.
When you say cover, what do you mean... screen protector film, or rubber bumper
I had this happen to my S0, I did hit it on something, cracked right across the top edge, where it rounds down, but there was an obvious point that it hit, The watch still worked though.
If you've got AppleCare, you can get a replacement for $69
without, it's $229 - $329 depending on the version.
The fastest way to do this is to call,
let them place a hold for the full watch value on a credit card.
They'll ship a replacement,
once you get the replacement, return the broken watch within a certain time.
once they get the broken watch, they'll release the hold.
If you don't have a credit card that you can use, it will take longer, as they have to ship you a box, and then you have to ship the watch back, before they send the new one.
Not sure if you can use a debit card, as the authorization might place a hold on your account.
you can make a genius appointment, but they normally don't have replacements in the store, so you'll probably have to do the mail replacement anyway.
