I once had a damaged Excel file that defied all of the fix-it methods on the web. Here is how I fixed it:

1. I plugged my Android phone into my computer via USB.
2. I copied the Excel file from Windows 10 into a folder on the phone.
3. I opened the Excel file with the Android “File Manager” app.
4. I made a small change to the file, and saved it.
5. I copied the file back to my computer.
6. Excel could now open the file.

So, the Android File Manager app didn’t share the same bug that was present in Excel and was able to save the file cleanly.