Angry Walter by Dee Dixon

from dedwoodcrafts.com:

Walter wasn't always angry. He was the world's best robot-friend, but time passed and the novelty wore off. He was left to rust in a junkyard alongside other abandoned robots. Walter swore revenge and started patching himself with whatever parts he could scavenge. He then began building his army. With his minions behind him, Angry Walter would emerge from the forgotten fields of misshapen metal mad as hell and ready to exact the revenge he promised on mankind. For humanity to have any hope of surviving his robot rage, you must find and remove his green power cell before it's too late. Stay calm as you make your way into Walter's inner workings and discover the tools and tricks you need to protect us all. It won't be easy, but the moments of discovery along the way will keep you from going mad. Now go forth and see if we can still be saved!