I recently repaired my lumia 920 screen, and the manual that i found was named "Nokia Lumia 920 RM-820_821 L1L2 Service Manual v1.0.pdf" I think it might be a internal document from Nokia. But it has detailed step by step. See if you can find it on google. The battery is not very hard. There arent many things keeping you from getting to it. But i wouldnt do it w/o the manual and the right tools.