[apple900]

I messed up, I jailbroke my Kindle K5 (b011) and didn't turn off auto update correctly. So now I have Kindle firmware 5.3.7.3 . I believe this is the reason for some of the problems I am having with KOreader. I noticed there is a downgrader for the K5 but I don't know what firmware to downgrade to and where to get it. so I'm looking for what firmware I should downgrade my K5 to. Thank you