When a bullied kid finds a terrifying but badly wounded alien, he rallies his family and friends to help get it back to it’s spaceship.

Okay... I thought adding "terrifying" would differentiate that this wasn't the lovable E.T. we all love.

So, here's my reworking:

After being nursed back to health by a school boy, a wounded alien is forced to reassess it's plans to invade the planet.

Agree with all the comments above. Sounds too much like ET right now and needs a description that distinguishes from that movie.

How about E.T. with a kick:

"When an injured alien threatens to destroy the earth, a terrified teen convinces the creature to give him twenty-four hours to return him to his space ship, if he'll spare the planet."