Are we sure that this device is actually using Parental Controls? The phrase "Managed Device" makes me think that it is part of an organization's stock of Kindles using Whispercast--I know that some schools use this, and some businesses, too.
If that is the case, then factory reset is also probably blocked. Where, exactly, did this Kindle come from, again?
https://www.amazon.com/gp/help/custo...deId=201115980
Shari