He was wondering or exploring, I don't know. He came into a place like a crash scene with a big dead robot - not that big, a little bit bigger than a human - and the boy had some kind of pet or robot with him and he accidentally tried to put his hand in the dead robot's arm and it activated, then he couldn't get it out anymore. Later he learned the power of the robotic hand and that the hand held great power. The desert was like a plain and the place was not like a usual place.
Can you please let me know the show and episode name? I'll be glad if you can help me. He looked like a little or young boy to me, and the robotic hand was not that metal - it looked kind of like a glove with LEDs on it.