Flash the 4.4.4 update via twrp. I don't know any other way. If you don't want to do that, then post your question on the V510 update thread in the general section.
I've tried flashing via TWRP, and it keeps failing
Go here, to this new thread > http://forum.xda-developers.com/lg-g...-twrp-t2797883
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