There is the generic expectation, that the brand represents the identity of the company to the public.
Generally I would reduce the brand to 3 challenges
The non-interchangeability, easy to recognize, hard to interchange
The persistence; there are brands, which never changed, and it seems they stay forever. Other brands get refreshed from time to time to accommodate with the spirit of the time. And there are brands which are put in place totally new in case of reorganization.
Truth; the biggest performance of a company and the brand. Sometimes a heavy burden for the brand.
As a conclusion we can admit that the brand can never be the repair-kit for major mistakes in companies. The goodwill in the balance-sheet of a company is a fragile asset and is always in the focus for critical questions. We can assume that there have happened irreparable mistakes in the organization, if the goodwill must face depreciations.