One thing is for sure, zero chance of fixing that. I would say the seat must have also twisted to cause the crack. No wonder with 6 " seat post dangling.
I would deny that claim as user caused. Get a proper size frame next time.
Now you see why there's zero at any LBS I want to buy. Changing the crank 1x to 2x is correct but still laughable. Find a bare frame.
Yesterday I saw a YT video suggestion, "Was 1x a mistake? LOL.
Looking at the ADV.1 ad they also show a 6" post on a medium, with a shortie head tube. LOL Nuts.
This does show a triple, is that on the new one?

Tourist in MSN should trade his yellow Thorn bike sitting idle, because it's 'Too heavy" LOL.