Here is my idea, It's pretty much like the newer show.
Eternia, a futuristic yet medieval culture. It's king believes in piece but rules by a strong hand. His sorcerer wants control of his kindom but when found out by his treason a curse is put upon him by the ancient sorceress of grayskull castle, That because he is so evil he shall show his true face so that anyone who sees him will know his heart is dead like his soul. After the curse he is banished to the deadlands of eternia as a prison sentence. Skip ahead 15 years a boy who is shy but with a heart of gold is sword training with his teacher. He is very reluctant to be offensive but is a great swordsman. The boy is Adam Prince of Eternia. It is his birthday the king gives him a beast named cringer a trained protector and pet only meant for loyalty this cat is gentle and very loyal but nasty when provoked. The king's most loyal general Man At Arms also has a present for Adam The Sword Of GraySkull. Lengend says it brings out the best in the bearer who weilds it. Upon recieving the sword the sorceress recites the chant By the Power Of Grayskull show me what lies in his heart as the vision happens the sword takes over Adam His clothes turning into smoke and then into armor his body Growing at a rapid pace the boy then turns into a man a HeMan(heymaan) an ancient warrior once known to eternia as a savior and prophet athat was fortold after he died his soul would be reincarnated into a chosen one when an ancient evil would arise to take over eternia. He-Man Then Grabs the sword And yells BY The POWER OF GRAYSKULL! the energy and magic and reinvigerates the soul of adam I HAVE THE POWER! He then colapses and is turned back into Prince Adam. He is told of skeletor The ever sorcerer. And later on the kindom is attacked by skeletors forces and the battle begins between heman and the skeletor.