Borderlands (JP)

House of the Ned is the third mission in the DLC:
1. Welcoming Committee - Recalibrate the 3 defence turrets to shoot zombies.
2. Is The Doctor In? - Go to Doctor Ned's waterfront clinic.
3. House of the Ned - Go to Doctor Ned's house in the bayou.

For House of the Ned you will need to make your way to Ned's house, once you make it to the mission marker you will have to speak to Dr. Ned over the intercom, this begins an event where dozens of zombies spawn while Ned hand-cranks the elevator down to you. You dont need to kill them all but hold them off till the elevator has landed, once open go in and use the level on the left to go up the elevator. Then follow the walkway around to the door open it and speak to the doctor to get the achievement.

I highly suggest you go see Zombie TK Baha before you make your way to Ned's house, more details here Solution for Braaaaaaaaaaaaains! In Borderlands (JP)