There is a way to open corrupted notebooks (all kinds of Wolfram Files)
You may try the following:
1) In the "File" menu you click on "Open..."
2) You select "File of types" for "Wolfram Files" (this enables the "Options" button)
3) Press "Options"
4) Enable first checkbox "Parse and load entire notebook in memory ..."
5) confirm and report me your experience.
The images were made under MMA 11.0.1 on Ubuntu, just for orientation
To be honest: I never tried this procedure in my life.
But this is the theory,(for rebuilding FileLeader+ FileTrailer+...) I found some times ago in the documentation.
Good luck, hieron