Load slot 1 or 4 and your right near the end just have to kill the boss use Laser Gun has infinite ammo 2 phases of the boss when dead the ending will show and your achievement will pop before the credits roll :)

Also other save slots may contain 1 or 2 endings in them not too sure but i think Ending 5 is in slot 2 or 3 but well seen loada people requesting for Ending 2 and so here it is hope i helped put in your ID's and then put on USB or mem card using Horizon or 360revolution.