Holding a CB in, or replacing a fuse with one of a (significantly) higher value is highly dangerous. The last time I saw it done, it resulted in the total destruction by fire of a Jaguar Mk X on its way to a car concourse when the wiring loom overheated and started a fire behind the dashboard which spread with terrifying speed. I was witness to this.
It is hard to imagine that professional flight crew would have held in a CB for more than a few seconds in a last ditch attempt to solve the problem, but desperation and fear are strange motivators. I hope the crew are exonerated from this.