USMT.mig file help

My computer is starting to glitch out and I had to do a clean reinstall via Dell SupportAssist.  I selected the option to create a and transfer a backup once the reinstall had occurred.  I had to reinstall Thunderbird which I believe overwrote the old Thunderbird profile with a default one.  I need to be able to access the USMT.mig Do_Not_Delete file to access the old Thunderbird profile.  I assume it's in there because the Firefox profile was copied over fine with all of the latest browser history.  Using the USMTUtils is a bit over my head.  There must be a way for me to view and extract that one file? Any help is appreciated.