Some missions in Borderlands 4 have obscure objectives that don’t have clear indicators. This applies while completing the 5th main mission, One Fell Swoop. While going through the steps to complete the mission, you get an objective to remove armor from the door. The only problem is, normal bullets won’t work here. This guide will explain how to remove the armor from the door in the One Fell Swoop mission in Borderlands 4.
One Fell Swoo – Remove Armor From the Door Guide

To remove the armor, pick up the explosive canister from the contraption opposite the door and toss it at the door before the beeping stops. You will reach this point after arriving at the lab and dropping off the Locust sample in the Dissected Plateau. Zandra is the quest giver here, and you need to find a way to escape the lab and get to her, which is where you need to figure out how to remove the armor from the door.

To find the explosive canister, head back to the terminal that you interacted with earlier to drop off the locust sample. To the right of the terminal is a contraption; interact with it by pressing down the right stick (console)/ V key (PC) to grab the explosive. As soon as you hold it, the canister will start beeping and will continue to beep rapidly. You need to aim and toss it at the door to break it down before it explodes in your hands.
Once that is out of the way, continue with the rest of the mission to return to Zandra. You have to perform the grab and toss of the explosive two more times: once right after leaving the lab and on the way to the airship, and the other time while trying to kill the armored brute. During both times, interact with the contraption within the area and collect the canister, then aim and toss it at the target to destroy the armor.
You will encounter more enemies as you progress through the Borderlands 4 missions, so check our boss fight guides on Sidney Pointylegs and Splashzone to know more.

