Regarding the 14 day return policy:

You must not have viewed or printed, in total, more than five percent (5%) of the e-book.

-- from <https://global.oup.com/academic/help/ebooks/?cc=ca&lang=en&#...>

According to that I'm not covered because I tried to print more than that percentage of the book to PDF (and was presented with the kind of unusable garbage output shown in my post).