Sim tray and back glass don't fit after display replacing

Hi,

I broke the front glass so i replaced it with one bought on the internet. I followed ifixit's guide step by step and everything went ok, i also replaced the battery at the same time and that works great too apart from the sim tray which is stuck open. When i insert it with or without the sim card it doesn't fit perfectly and is about a millimeter out. The back glass too won't slide back and i think it's because the part over the sim tray is lifted a little bit too much. Does somebody know how could i fix it? I really don't know why everything's not in the right position because i followed perfectly the guide and every passage was ok.