Standard procedures for maintence is to tag a breaker when it is pulled.
Might be SOP's for maintenance, but I'm sorry to say as an ex Engineer that SOP's are not always followed.
Not saying this was the case in this incident of course - how would I know - but the possibility is there.
Despite that, the responsibility for checking CB's rest with the Crew before flight and also when a system fails (easy to overlook in the heat of the moment I might add)