If you've soldered on your ESC several times, try taking the case apart, and clean between the solder posts, as well as the bottom side of the board where the solder posts are attached with denatured alcohol and a stiff nylon brush [tooth brush style], blow it dry with compressed air, and don't apply power to it for at least 20 minutes [to be sure everything is dry].

I've seen this happen due to a high resistance short due to uncleaned solder flux on the RS that was remedied by cleaning.

You might have still fried something running without a cap, but if you have to wait a bit before you have the funds to send it back, it might be worth a try.