BOOTCAMP backup image iso destroyed ???

I recently split drink on my 2017 macbook pro 15 inch. Long story short, everything works but the internal display or screen (even tho the backlight still lights up sometimes) so that cause the dreadful bootcamp partition unmounted being greyed. I made a backup image of the partition through disk utility like 951gb image dmg, as I used most of the 2tb hard-drive for windows. Once I restored the partition with bca not only did I find out I couldn't install windows with a external monitor but also the backup iso image dmg doesn't even mount (unsupported)even tried converting the file to try on pc, gives file (corrupted) error.

Im just holding on to this file now, hoping there's something that can be done. If I could get that data back, I'll be very grateful. Any help will be appreciated greatly