XML minidom parsing error

I am trying to parse www.amazon.com source HTML as follows using xml minidom.

def start_parser(self, analysis_id, url):
    dom = None
    path = self.create_analysis_folder(analysis_id)
    self.get_generated_html(url)
    for root, dirs, files in os.walk(path):
        for file in files:
            if file.endswith('.html'):
                dom = parseString(open(path + '/' +file).read())
                shutil.rmtree(os.getcwd())
        break
    return dom

The method does some basic folder manipulations and then calls parseString giving it the html source code. I get the following error on execution.

xml.parsers.expat.ExpatError: not well-formed (invalid token): line 20, column 20

Can someone please explain what that means and how to get rid of it.