Lockdown is just locking down the bator, as in not opening it. It usually takes place at day 18,whenver you stop turning the eggs, you add water to up the humidity and lock down the bator and don't open it so that the heat and humidity doesn't fluctuate to much in the last few days. Although if you do have to open it, you should still be ok. Just try to not open it if you don't absolutely have to.
Your incubator doesn't have a way to add water without opening it? I have a home made incubator but if I have to add water after lockdown I just use a syringe to add water through one of the holes I've poked in it. Not as quick as opening the lid and pouring it in but it keeps my humidity steady.
Try not to open the lid at all after they start to pip if you can help it. It's more important after they pip than any other time until they hatch. From what I understand, after chicks start to hatch, their own moisture adds to the humidity inside so that should help.
Humidity question during lockdown....I locked down on Day 18 after filling troughs in Little Giant and adding a wet washcloth in shallow dish. It's day 20, I hear chirping, and I just noticed the troughs are dry...washcloth still saturated. Do you think my humidity is ok?