New snake struck and then laid out on back

[Albert Clark]

I believe what you witnessed possibly was the extreme ending of all that energy that’s expended in a juveniles hunting , coiling, and killing of their prey. As was described earlier, they are new at it and still figuring the methods out. They tend to be very exhausted afterwards. Just look at their breathing and respiratory rates after making a kill whether f/t or live. They lie there momentarily and sometimes for extended periods making sure they themselves are not injured or in pain. Of course also, that the prey item is disposed of and doesn’t pose a threat to them.