Yep, that sounds like fried ESC!

First electric stuff I got came without connectors. I couldn't find anything about which way the polarity should be on the Deans plugs (no marking on the plugs) so I soldered them all up the same way. As I got new bits I duly sodered connectors on being sure to stick with the same convention.

All way welll until I bought a new ESC that came with a connector already on it! I plugged it in without a thought, with the same results you got. The way I had been connecting my plugs was the opposite of the rest of the galaxy!

BTW, you don't mention battery charger. You know you have to have a special charger for Lipos, and that you have to take some care when charging them.

Terry