Autonomous robotic systems for various applications including transport, mobile manipulation, and disaster response are becoming more and more complex. Evaluating and analyzing such systems is challenging. Robotic competitions are designed to benchmark complete robotic systems on complex state-of-the-art tasks. Participants compete in defined scenarios under equal conditions. We present our UGV solution developed for the Mohamed Bin Zayed International Robotics Challenge 2020. Our hardware and software components to address the challenge tasks of wall-building and firefighting are integrated into a fully autonomous system. The robot consists of a wheeled, omnidirectional base, a 6 DoF manipulator arm equipped with a magnetic gripper, a highly efficient storage system to transport box-shaped objects, and a water-spraying system to extinguish fires. The robot perceives its environment using 3D LiDAR, as well as RGB and thermal camera-based perception modules and is capable of picking box-shaped objects and constructing a pre-defined wall structure. Its sensor modules also facilitate detecting and localizing heat sources to extinguish potential fires. A high-level planner coordinates and applies the robot’s skills to complete the Challenge tasks. We analyze and discuss our successful participation during the MBZIRC 2020 finals, present further experiments, and provide insights to our lessons learned.