Unable to install OTA after un-root - broken stock recovery?

[Ninjatogo]

Hi there everyone, I've got a strange problem on my hands now that the new stagefright update is out for the M7. After downloading the update, I tried installing and was greeted with this:

Now I've never seen this before but I assumed it was because I was still rooted. So I then un-rooted (was previously rooted using KingRoot) and did a factory reset. Downloaded the update again and I'm still seeing the same result.

From what I understand, the entire system is scanned during the update procedure and things like root can throw it off. Given it's un-rooted and I've done a factory reset it should be working but the lines in the image above suggest that some actions I took earlier may have removed a few files from the recovery partition. Would reinstalling a factory image of the recovery fix this problem?

I'm using the generic EU ROM and I'm currently running 7.19.401.22

 

[Rukbat]

King Root leaves footprints, which the update check finds and it aborts. (You can do things to a phone when it's rooted that will cause an update to brick the phone - and those changes stay there after you unroot. Unrooting only unroots, it doesn't undo changes you made.)

Reflash a stock ROM (back EVERYTHING up if it isn't already - see Backing up an Android Device), then it should update.

 

[Ninjatogo]

Which would you suggest? I'm having trouble finding the RUU for lollipop.

 

[Rukbat]

Install any recent stock ROM you can - the phone should update after that. If not, Settings/General.About device/Software updates. (You can only do one update every 24 hours, so if you go back too fr it'll take while to get current, unless the current update is cumulative from your flashed version.)