Metal Arms: Glitch in the System/The Zombiebot King
From SDA Knowledge Base
First boss battle.
Ammo refills are along the back wall, as well as the rivet gun if you haven't acquired it already; after defeating the boss, Mozer gives you the level 2 rivet gun.
The first grate on your left contains a Fleet Foot booster, which makes this boss a lot easier to manage.