Some idea I once had for a better version for the Green Lantern movie:
The movie focusses mostly on Hal Jordan (after getting the ring by Abin Sur) being immediately transported to Oa, where at first the Guardians want to take away his ring, considering earth unworthy to be represented in the Corps. But as it turns out, the ring can't be removed and Jordan immediately proves he actually can use the ring subconsciously rather well. Being offered to stay at the Corps while the Guardians try to find out why Abin crashed on Earth (he was previously missing for months, supposedly investigating a big scheme by some enemies of the Guardians) , Hal is trained and eventually picks the curiosity of Sinestro. Sinestro, who wants to find out what happened to his friend Abin, decides to do his own investigation and forces/asks Jordan to help him, as Abin supposedly passed secret information on Hal also, Sinestro only was supposed to receive. Together they eventually find out that members of the Spider Guild are planing an uprising of the Manhunters, who serve the Corpse currently together with the regular Lanterns. But while they supposedly stop the guild, they are playing also in the hands of a certain member of the Guardians. Said member is Krona, who worked with the Spider Guild and has actually manipulated the Manhunters for centuries as his personal little army to cause conflict behind the back of his fellow guardians, to strengthen the Guardian's position as protectors of the universe. But now he has grown tired of the state of the universe and after researching the emotional spectrum for some decades, he has invented a machine that will allow him to manipulate the emotional spectrum directly and turn every living creature in the universe into an emotionless, willing, "good behaving" slave. Abin Sur had by accident discovered Kronas connection to the Spider Guild while investigating some other crime and wanted to warn his fellow Lanterns before he could initiate his plan, but Krona made sure his ship crashed on Earth first.
Supported by some other Lanterns, Sinestro and Hal manage to defeat Krona and destroy his doomsday device, which seems to take Krona's life. Jordan proves himself worthy of being a Lantern and the remaining Guardians decide to let him stay Abin's succesor, who then returns to earth and starts his life as earth's Lantern.
