I'm looking for a 3D cartoon where the main character finds a red robotic arm and it gets stuck on his right arm. The main character lives with his uncle and his cousin and has a robotic talking dog. I remember during one of his fights, the arm became a complete robotic suit. I remember in one episode, the main character kept thinking, 'Going straight is better than going around'.
Possibly Eon Kid (2007).
Marty is the lead character of the series. While scavenging for robot parts to sell he finds the Fist of Eon and puts it on, although unwillingly. Marty later discovers that he is a direct descendant of Eon, who 100 years prior to the series' start defeated the General and ended the Robot War. Endowed with the power of the fist he must fight the evil forces of the general. [...]
Buttons — Marty's robotic dog and good friend. He constantly talks too much and provides great comic relief. He has a stretched out tail, that stretches super far, and by twisting his ear, it puts him on bark mode.
Apparently it's revealed that the father he lives with is actually his uncle.
Found by memory of having seen a similar question here, namely Looking for a T.V. show - Animation - Boy can change into red and yellow robot with an arm blaster, which I found back with the site search
[story-identification] robotic arm animated.