Try to start and get two clicks, message saying "Smart Key not Found" green hill decent light flashing.

Jumped the truck and started perfectly. Drove to local auto parts store, they tested the system and said battery and alternator checked out fine.

Drove back home and would not start.

When I put a multimeter on the battery, I am getting less that 10v

It's the battery, right?

 

At least one cell broken on that battery, yes. I had some years ago a battery that gave around 9 V output.

 

It was the battery.

Goes to show you can't trust a kid from a auto parts store with a tester.

 

12.6 v after a full charge. It should keep the voltage level over night. Or I replace it.
Incidentally, I’ve learned Costco will replace 1 for 1 on a battery less than 2 years old. None of the pro rated nonsense.

Cheers