The XML needs to be valid for NORMA to attempt to load the file.
If you open this in the VS XML editor, then typing the less-than character (<) after the failure point will bring up an intellisense list with the close elements at the top. Generally, the best you can do is to match the close elements and see what is left.
NORMA always saves to a temporary stream, then dumps the entirety of the stream to the output file after the save succeeds. This is meant to eliminate file corruption from within the tool. We also use the standard .NET XmlWriter classes for writing XML, so it is highly unlikely that the tool will write invalid XML.
You can send me the file off line if you want me to see what I can salvage. I'm pretty familiar with the .orm XML.