think this might help you.
There are 3 endings
The first, which was the original ending to the film (and in my opinion the best), has Jim dying from the gunshot wound. The whole scene in the hospital is actually shown with Selena and Hannah trying to revive him and failing. When they face the fact that he is dead, Hannah asks what they're going to do. Selena realizes that she is now responsible for the girl and picks up the firearms, giving her a pistol. She says "we move" and the two of them walk away from the camera, down the corridor as the steel doors slowly swing shut. Definitely the most depressing but powerful ending...I was lucky enough to catch it in theaters after the show.
The second ending is almost identical to the theatrical release, with them forming the huge HELLO sign from linen, only Jim is not present, it's just the girls. As Boyle and Garland put it in their commentary, he was replaced by a chicken...you have to see it to understand.
The last of the three is not so much an alternate ending as it is an alternative version of the entire film. There are no soldiers. The story takes off in another direction once Frank (Hannah's dad) becomes infected. Jim is holding the bat but can't make himself kill him so they tie him up before the infection fully takes hold, and drag him with them. They search the blockade area and come across the original testing lab from which the infection began. There is a man in an isolated, impenetrable room who says he has the answer to infection but will not tell them what it is or let them inside. The film continues from there for a while and then Jim brings Hannah to the room and yells to the man that she is fourteen and her father is infected, so if he has the cure he'd better tell them what it is for her sake. The man says that since the infection is in the blood, one of them must give a full body transfusion. They take a sample from Frank and find out that Jim is his type. So Jim switches his blood with Frank's and becomes infected while Selena, Hannah and her father join the man in the safe room. I personally LOVE that version and I wish they'd made it because, while I liked the soldiers, I thought this gave it a more personal feel. This version, however, was not filmed. It was conveyed on the DVD through Danny Boyle and Alex Garland, one reading the stage directions and the other reading dialogue as they played through detailed storyboarRAB. Very well done though, it really made you feel like you'd seen it for real.