X Factor's Epic Fail -- REJECTS Next Justin Bieber

"X Factor" -- the freshly cancelled singing competition show -- didn't help its chances of survival by booting a contestant who could have become the next Justin Bieber.

17-year-old John Lindahl auditioned for the show back in 2011, and eventually got kicked off in the second round.

Apparently ... Epic Records honcho L.A. Reid -- who was also an 'X Factor' judge at the time -- saw something the show didn't, because he immediately signed the Bieber look-alike to a sweet 5-album deal.

We got hold of the legal docs showing John is getting a $300K advance for his first album, and gets a pay hike for each subsequent album ... which could eventually land him up to $800,000.