(Typing from Hudl)
I have a rooted Hudl, with all tesco branding removed, apart from the updater and the legal stuff. Including a modded SystemUI with no T button.
I tried to update to 1.3.1 and it fails at bootloader, saying error with a android open and a exclamation mark in a triangle. Entering recovery says that Books. Apk is missing. Tried twice and same issue