Help with KDZ and flashing ROM?

[MJLgaming]

I rooted my phone a while back then unrooted it but deleted too many apps. Now its on a boot loop saying "security error" factory reset wouldnt help. I wont pretend to know much about ROM's or flashing them or what a KDZ is but its my understanding I need to find a KDZ for my phone the LG Phoenix 2 or LGK371. The OS is marshmallow 6.0 I believe. What KDZ do i need? Will flashing the stock ROM/Firmware fix my phone?

 

[MJLgaming]

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