Fix PowerPoint file from iPad that was saving in iCloud within an hour - I'll pay only if problem is fixed please

Please can we agree that I'll make payment only if you succeed in recovering the file within an hour, but not if you do not succeed. If it is not fixed in an hour then we will need to start making the file from scratch. The tech experts at the university after trying for two hours have been unable to fix this. We were making the Powerpoint presentation for several days with no problems, it was automatically saving to iCloud on the Mac, then suddenly it stopped working today and when we click on it, it says "“[Filename].pptx” can’t be opened right now. The file format is invalid." There is no backup file on iCloud or on the iPad. If you can fix this file that would be great. Please see the file, it is attached