The trail was all there, on paper and in computers, but, as posted, high radiation prevented access to it. Hindsight shows that data, as it is recorded, should be transmitted to a central site where it can be studied, and (hopefully) errors corrected immediately.
(provided transmission lines or microwave towers remain serviceable!!!)

I am sure that the situation was hectic, that no very senior engineers were on hand, and attempts to control the reactors were "off the top of the head."
Remember that two workers were killed on site- possibly the ones who attempted to shut it down.
Still a lot of the details not yet known-