Can't install OF1 even after root is removed.

I wanted to update my phone to OF1 but every time I try to update it says that the update failed. I tried Uninstalling root using super SU and root checker claims that root is no longer installed however every time I boot it does that black screen with the word "custom" on it. Is their a way to make it so that I can accept the OF1 update? (Especially since I just learnt of stage fright which that is supposed to fix).

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