I ****ED UP

I was messing around with my LG G3 LS990 because my internet kept saying something wrong with proxy or something and I pushed wipe dalvik cashe and cashe in twrp recovery and now when I try to boot up the phone it shows the logo then shows it again and underneath says security error and I tried to flash stock rom using download mode but it says download mode is disabled by kill switch somebody anybody please helppppp