Follow the hallway and go through the shuttered door. Drop down to the lower level and exit the far side of the room through the other shuttered door. Turn left and go through the door at the end of the hallway. Drop down and face the new enemy here.
The stun baton enemies aren't difficult to understand but they can be a pain to deal with. Stun enemies can't be countered in any way and you can't attack them from the front or you'll be stunned. The only way to deal damage to them is by jumping over them and hitting them from behind.
Deal with these three enemies. Once you are done with them, you'll be beat up by another group of enemies and you won't be allowed to react. Once you regain control, pay it all back. Beat them good. You've got a little bit of everything in this group so be careful. Watch for a gun, shield, and stun batons as well as occasional thrown items. When you clear this wave, the next wave will come with no weapons but one of the enemies is armored and there are plenty of weapons on the floor. Try to make quick work of them before they can get any weapons. Bounce the bozos and head through the manhole cover off to the side.