icebunny, rest your mind, there is nothing to worry about. You may think she burried them alive but that's not the case
I have kits born in burrows in my pet rabbit colony and it seems as your doe is doing fine!
She is only doing what is natural, closing off the entrance of the burrow so predators can't locate it.
At feeding times, she will dig the entrance open, nurse the kits for 5 minutes and leave the burrow and close the entrance again.
I know it looks like she doesn't care but she does visit the kits 2x a day, often early in the morning and late in the evening.
They will pop out of the burrow eventually around the 3rd week but they will quickly go back inside if they hear a sound.
It will be VERY hard for you to catch them. By the time you walk up to the hutch and open the door, they are back inside the burrow.
Burrow rabbits are very skittish and tend to stay that way.