You need to find a button to open the lab doors in one of The Contract’s DLC missions. This guide on How To Unlock The Lab Doors In GTA Online will tell you where to find the button so you can open the lab doors and escape before returning the van back to the agency.
Much like other objectives (such as finding the safe combination or opening the hangar doors) certain parts of this mission can be random. You must fight your way through the Humane Labs interior before eventually arriving in the garage. Once in the garage the animal you will need will be in one of the trucks. After you enter the truck you will get the objective asking you to find the button to open the lab doors.
How To Unlock The Lab Doors In GTA Online
There are likely multiple spots for finding the button to open the doors in the lab. This particular spot is very easy to find as it’s right next to the doors. Be careful, as you approach more enemies will spawn in behind you. Further enemies will spawn once you press the button, so be prepared for a fight, especially if you’re playing solo.
There are likely other locations to find the button to open the lab doors in the Humane Labs. We’re going to keep playing missions and will update this post if other locations are discovered.