If I had to guess, it wouldn't be profitable in making repairs... mostly because people aren't going to be willing to pay a reasonable price for hourly work. I've got a CNC and there's only been 1 time where someone has taken me up on an offer for custom services. In this day and age, folks typically expect to pay the same price for a mass produced product and don't consider the level of work that goes into manual labor. Generally it will be more cost effective to replace than to repair.

Regardless, it may be worth contacting HobbyWing or Tekin and explaining that you have a competing brand of ESC that has gone bad and see if they are willing to offer you a discount to trade up your old ESC for one of their new ones... chances are this cost will more than likely be less than if you were to send it in for repairs