Seriously I dunno just which is better
U overhaul the entire line on Friday, check all the train and
tracks… Declare non working day.
If still cannot finish, continue on Sat.
This kind of thing cannot say try n resume asap
If the line has to be closed for one day, the inconvenience is
expected. People can make arrangements to get to work on time.
If a major breakdown actually happens, it's unexpected. By
nature, even your own recovery arrangements and shuttle buses will
be slow to activate.
Option B is hoping you won't lose face. But in the end, you lose
even more face.