help security error

ok so i was trying to update my phone with a root img i found with the new update so i did what was needed but something wrong happened and now im stuck at a security error screen

but im able to get into download mode an my computer reconizes my phone but i am able to push the update through download mode but same thing when i try to reboot a security error pops up

i know its flashing and connecting because i can command my phone off from computer

so is their any way i can flash a file straight from my computer to download mode without it on my phone