Need your help guys G2 lolllipop topic

I bought a used LG D802 from a shop and found that its case and software says it is LG-D802 running sotware version D80220c. But when I looked up its IMEI I found it is D800 AT&T. Now the problem is that what should I do to update it to Lollipop. LG Mobile support tool says software is up to date .
If I want to flash through kdz which kdz should I use? Please guide me