been there, done that. what I did was to remove the old floor completely, then use 1/4 inch oak plywood to fab a new floor. I used oak as I already hat it in my stash of odd pieces of wood :o)
I had to make the floor in 2 pieces so that I could get it inside the cabinet. I used a piece of furring stringer to make the joint at the center of the floor, first securing with glue and screws on one side, then installing the second floor piece using only screws to secure it. covered the new floor with shelving paper and the repairs are out of sight :o) took about 3-4 hours to complete the job.