Gather some T-ENG from the containers up ahead and get into the VS. Jump down, where you'll face a large group of Akrid elites. Activate a Data Post and enter the tunnel, you can switch your VS for a better one here. Jump through the hole in the roof and head towards the light up in the cavern. You'll see a hole in which you can drop, do so and follow the corridor until you reach a path labeled Area 011. You'll end up in an underground city, or at least what's left of it now. Turn left and go down through the tunnel.
There's a huge Mantis-like Akrid here - if you don't have a VS anymore, just skip the fight and run towards a ruined building (right screenshot below). Enter it and drop all the way down. Grab a Laser Rifle and attach it to a VS down there. Board the mech and proceed further, only to find yourself engaged in a boss battle.
This battle can be divided into two phases. The first one is to eliminate the feelers. It's best to do so on foot, so leave you VS for later and start to attack them. Whenever you deal enough damage to a feeler, the monster will withdraw it through a tunnel in the floor. Enter that tunnel and his the boss' body from there (it's good to have a chargable weapon, like VS Laser Rifle, you can load a shot when entering the tunnel). You'll have to do this two times for each feeler. When you destroy the feelers from the inside, the boss won't draw them out anymore and you'll be able to attack it directly.
The second phase is very simple - get in the VS and try to jump and hover all the time, throwing everything you've got at the Akrid's red head whenever it shows it from under the shell. It won't be able to take much, so you'll quickly be done with it. Your main concern in the second phase are the lesser Akrid wandering around the arena, including the electro-charged squids. Don't mind them, focus on the boss and keep jumping. When you defeat the monster, go through the door that'll be revealed behind its body.
Grab the EM Laser and activate a Data Post. Go forth and destroy the turrets. You'll end up in a huge industrial area in which Nevec forces are fighting the Akrid. Take advantage of the mess and take everyone out one by one. You'll find a few Data Posts here, as well as any VS type you can think of. When you're ready to proceed, go down (looking at the PDA map).
Jump down to the VS storage area - sure a lot of mechs here. Fortunately most of them are offline. Defeat all the enemies and reach the opposite end of the hall. You'll see a passage labeled Area 011. Jump down there to meet the gruesome Bandero.
Bandero can be a pain if you don't press him enough from the very beginning. Arm yourself with a VS Shotgun and an EM Laser (it's to the left of where you start the fight), and then charge. Get close to the enemy and stay that way, he's much easier like that than from a distance. When he uses his lame paralyzing attack, back up a few steps and let him have it.
He has a wide variety of attacks, including plasma, rockets and probes - you really don't want him to start using it all. Be quick, attack him at once and try to take him out as soon as possible. The EM Laser should help you a lot. Don't mind the probes that are flying around the area, your goal is to defeat Bandero so quickly that they won't have a chance of harming you.