In my area the eggs would be fine with the humidity levels in my house. So a cardboard box with a heat lamp above it works for a few days.
Of course I would have to be careful that the light is far enough from the box without being too far. Inside your brooder might be a good idea.
The ideal is to not open the incubator. It just doesn't always work that way.
Please keep in mind you might not need to assist at all.
If you need to open the incubator the goal is to lose as little of the heat and moisture as possible. I find that a hand towel that is damp with warm/hot...