home button worked bad, needed big force. I tried to clean it but didn't work much better.
Well, harder than I expected! I'm very far to be a novice. Battery removal went very hard. It was bad glued to the base. I did not realize that if you are not extremely careful you need a new one. When I put the phone back together it worked perfectly but it didn't charge (even it showed that was charging). When I removed the battery I did something wrong most likely to the flexible tape. I ordered a new battery and the phone works perfect.
I almost lost also two pieces during dis-assembly: a small rubber spacer (step 18) which was loose and a nut (step 19) which was also loose. I made also a mistake when I re-assembled the battery by putting the small metallic ground contact (removed at step 5 and 6) over the battery plate contact not underneath it. It's possible that this mistake caused a small cut on the flexible tape of the battery contact.
I wish I had known that the battery removal (especially the flexible tape and contacts) needs much more attention being very fragile. Take your time to remove the display (step 28) which is not easy. The plastic tool (if you have only one like I did) is most likely spent when you are there. Carefully insert a fine blade (even a metallic one) between display and frame at a corner, only to make a small space to insert the plastic tool. Place the removed screws in a compartmented tray with labels.