I think you’re right, it’s just not a suitable environment. I bought two from Meehan’s Miniatures, and one from a vendor in Buffalo. That’s the one in the photos. I really liked that one 
I am sorry @A.Cole411. One other issue that I can think off is watering. A few years ago I had a larch that I took a chance to repot a bit later, still not in full leaf but buds definitely breaking open and then we had a bad combination of a wet spring and me still not knowing (the hardest thing in bonsai) how to water and it wilted away and died… You should try to get in touch with the people that sold the trees, if they didn’t repot at the right time they may have contributed to the trees’ demises.
Thanks, raft. I really don’t feel like she owes me anything, though. It was my fault that I left it in the sun and heat