Parsing text/part1.xhtml ...
Initial parse failed:
XMLSyntaxError: Start tag expected, '<' not found, line 2, column 1
If I am getting this figured out

You have a malformed part1 file.
Use Tweak (tap T with the book selected and expand. Open part1 with notepad..) Line 2
BTW, it would not hurt to validate EPUB's with Flightcrew