A Korean Consulate cannot arrest you and deport you back to Korea so it would be safe to go in. I recommend going with a family member or friend who is more fluent in Korean. By the way, was there a reason why you did not apply for military service deferral before turning 25? I did mine and got deferred until age 38. Also, I do have a friend who was in the boat as you (didn’t apply for a deferral before 25) and he got his GC just fine via AOS. Now whether or not he can visit Korea without getting arrested at the ICN airport is another story…