The Shaft

Once you've reached the location, find a manhole nearby and enter it. Use the REC to disable the generator and allow you to get past the flooded corridor. Once you're out of the water, reactivate the generator to lower the gate and allow you to continue forth.

Grapple to the vent and you'll be under the floor with a lot of armed militia. Switch to your voice synthesizer and order one of the militia personnel to open the gate. Switch control to your Batmobile and incapacitate all the guards. Switch to Batman once cleared and rewire the fuse box to open the gate.

Switch to the Batmobile again and target the weak wall in front. Use Batman again this time and grapple on the metal beam in the middle of the ventilation shaft and swing again to the next ledge to activate the lever and lower the barricade that will allow the Batmobile to get in.

Attach the power winch and slow lower the Batmobile down the wall. Look up and you'll find another damaged wall. Destroy it with a blast. As Batman, grapple in the middle beam again and grapple to the newly opened hole. Turn around and you'll see a Riddler Trophy on the workbench. Equip the REC again and start shooting electrical charges on the generator to power down the fan.

Now enter the Batmobile and lower it further. Shoot the next cracked wall across the shaft and shoot the militia guards. Eject-glide to it and find a vent to the elevator shaft. Grapple to it and stand on top of the unpowered elevator. Use your REC to power it up. Shoot it twice so it goes down two levels. Now blast the cracked wall with your explosive gel.

Two guards with stun sticks are waiting for you. Quickfire your REC (L2 + circle) to temporarily stun them and remove their sticks. Finish them off and pull down the lever to open the gate. You'll find the next generator but it's behind a thick glass wall. Ignore it for now and make your way to the next corridor.

There's another riddler trophy behind the gate. Take note of its location for now then grapple on the next ledge and use your REC to power up the generator and electrocute the militia guards standing on the puddle. Pull the lever down in the end of the corridor then enter the next elevator.

Press R1 while using your REC to make the elevator go up. Blast the next wall to reveal another Riddler Trophy.

Now make the elevator gown as far as it goes. Climb out and enter the alcove beside it then make the elevator go up so you can go down the shaft. Grapple the next ledge and enter the grate. There's a bunch of militias there so before diving in, make the proper preparations like sabotaging the medics' resuscitating packs and the ammo crates. The militia leader is also wearing an explosive vest so make your way behind him and disarm the vest from behind the sheets. You have to engage the remaining militia on hand-to-hand combat.

After defeating them, use the fusebox nearby and continue to the shaft again. Drop down to the ground below and enter the opening. This path is guarded by a sentry drone. Use your RHD to temporarily blind it then quickly get on the elevator shaft across it. Grapple on ledge above and you'll reach the next generator. Overload it with REC and you should be able to lower the Batmobile.

Attach the power winch to any of the four available hooks and pull it to the left so that the drill platform goes down. After reaching the bottom, destroy the cracked wall and destroy the sentry gun in front of the elevator shaft so Batman can go down safely.