how long was it kept there? actually, more importantly, what did the mash schedule look like before then?
At that temperature all the enzymes are killed off that are responsible for converting the starches into sugars for the yeast to process. If you alreayd had your sugar profile, probably no difference, if you basically went straight to 170 with little time for conversion in the lower temps, you probably are looking at a very high FG. Undrinkably high