I doubt you can do anything to get the brake back... assuming you've re-calibrated already. The brake is usually the first to fade and eventually go out completely before the rest of the ESC dies. This is common for overworked ESC's.

You can contact HW to setup an RMA, and they will typically offer you a deep discount for a replacement since your ESC is outside of warranty:
https://www.hobbywingdirect.com/pages/rma