I've got a 2010 Suburban that for the last 4 days wouldn't start from the cold. It's been average -15C here. Today is +3C stars right up, no issue. New battery in June, have it on a onboard trickle charger, didn't start. Tried boosting it would not start, now today it started right up, first shot.
I can't believe it's the battery, thinking starter. Lots of corrosion in starter, but open to suggestions??

 

Don't rule out a battery. In the last 15 yrs I've had 3 fail while still in warranty due to an internal open inside the battery. You could give the battery a rap and watch the headlights come on on one of them. Just being PO'ed and slamming the hood could make a battery come back to life. And carrying it into the store they would test OK.
Had this on 2 AZ batteries and on 1 DieHard.
I'm a Odessey battery guy now on vehicles I'm keeping long term and if they make one to fit it.