Default [Q] Is my phone completely bricked?

So I'm a retard and I installed the MK3 boot loader on my AT&T GS3 and accidentally deleted the OS. I can still boot into the recovery and download mode. I can't flash anything through Odin since the boot loader doesn't let me. Is there a way to fix this or is my phone completely bricked? If there is a way to fix this, please tell me how. Thanks.