How did Douglass succeed at coveys

I think you are referring to the incident in the barn. There is a scene where Douglas finally punches the daylights out of Covey in a barn. THey fight for like two hours until Covey gives up. Douglas says it's like being raised from the dead: paradoxically, he comes back to life just when he decides he would rather die than be a slave. And it isn't just a moral victory: from that point on, Covey doesn't mess with him anymore.

source (part of it)

How did Douglass succeed at coveys