The Hotel's Iron Guardian

Connor Jackson. A young genius, he was orphaned at the age of 8 when his parents were killed in a car crash that he somehow survived, even though the car was completely destroyed. He didn't survive unscathed, though. His arm was broken, his legs were broken, and he had numerous pieces of metal from the car embedded in his chest, nearing his heart. It was too close to his heart to safely remove, so they put an electromagnet in his chest, which they powered via a battery pack with 9V batteries. He eventually upgraded this into a much more convenient form, no longer needing to replace the batteries. Several years later, he wound up in hell while working on a device, accidentally opening a portal that he falls through. He discovers a place called the Hazbin Hotel, run by the princess, and starts staying there. He uses a robotics lab that the princess used her magic to add to the hotel, creating various high-tech armors for various situations, which get put to the ultimate test over the span of six months when Heaven and Hell are on the verge of war.