E70-Replacement battery

[Elvis 3.0]

So I swapped out my battery on my X ('06, 3.0, 115k miles) on Saturday afternoon as a precautionary measure. It was most likely original but not sure as I have had it since '08. Anyway I purchased the battery from Autozone and installed the Duralast H8-DL
Battery | 2006 BMW X5 AWD 6 Cylinders 3.0L EFI DOHC | AutoZone.com.

Anyway, basic install no problems. Then went to a movie with my wife and later to the grocery store and to return home with all successful starts with no issues. The car is parked overnight and I am back in the car around 1 p.m. Sunday to reprogram bluetooth and randomly do a coolant top off. Start up the car, again no problems. Everything is fine. Probably had the engine on for maybe 15 minutes or so, shut off as normal and walk away.

Cut to this a.m. and my wife comes back to the apartment and says the car is dead and won't start.

She said that when she turned over the key that everything light up for just a second and then went dead. We attempted to jump it figuring that we must have left a light on or something (again brand new battery and all) but it wouldn't take a charge. In fact, the only thing that remotely light up after a few minutes of a car to car battery charge was the red air bag light faintly in the cluster.

No idea? And what options would you take? I've changed few batteries over the years and this one wasn't special. I don't recall anything odd during the install and I certainly made sure all cables were secure?

My questions are 1) any ideas on what is happening? & 2) what would you do to solve this.

My initial thoughts are to go get a brand new battery, again swap it out, and cross my fingers. Did I overlook something? I am hoping it is not a coincidental timing with some sort of parasitic drain? And if it happens to be would a device like PriorityStart help and should I just install it?

PriorityStart Battery Saver - Stop Dead Batteries on Cars & Boats [Priority Start! Battery Protector]

HELP! (also gonna need advice with the wife after she blames me for the battery install and her missing her meeting this a.m.)

Thanks in advance

(p.s. as this original post was in E70 and battery issues can be universal I'm also going to copy over to E53 to see if this situation may be more specific)