mobile

ok so i upgraded to 5.1.0 (LMY47D) when it was officially released but i want to upgrade to 5.1.0 (LMY47E) because my nexus is actually a sprint nexus 6. when i tried to upgrade manually i was denied so im asking do i need to downgrade back to 5.0.1 so that i can upgrade to 5.1E?

Also i have unlocked/rooted my device and i had to use the boot image from 5.1E because it wouldnt accept the image from 5.1D when i wanted to unroot to try and upgrade. sorry just looking for help on what to do so i can actually get 5.1D