You start off facing the bunch of crystals, so ignore everything else and grab them. Turn around and shoot the TimeSplitter who killed Corp. Hart. As soon as you've killed it run for the door opposite the Time Portal as a swarm of insects will try to kill you. Take a left in this corridor and activate the machine you come across on your way down. Go through the first door on your left and follow the path along the left. You'll find armour and ammo. Go through the door marked "level 2". From here take a right and keep walking (ignore the door on the right) until you reach an active terminal. Activate that too and keep walking, ignoring doors until you come to the third and last terminal (you will pass one you've already activated on the way). Activating it will initiate the self destruct ti