Aleksandr Voronkov/Shutterstock A hacker in Germany was stunned to find he had complete control of a robotic lawnmower. Weighing over 200 pounds and equipped with cameras to navigate, Wi-Fi and 4G to connect to the Internet, and blades capable of pulverizing a human body, the Yarbo Lawn Mower has immense destructive potential for a hacker to abuse. And yet, Andreas Makris had gained total control over every active Yarbo robot across the globe with little effort. Thankfully, Makris had no plans to dominate the world with his newfound army of killer robots. He's a security researcher who spends his days…