If others have this problem like I did too when first changing the batter. Here's the answer not in the steps in the guide:
When reassembling the case after replacing the battery and closing the case you have to do the following. The top of the screen (where the cables to the LCD screen are connected) has to be slid in first, before settling in the rest of the case, so that there is no "bumb" on the top of the case. If you don't slide in the case correctly, you will get screen artefacts (after effects, ghosting) when pressing the screen in normal use. You'll notice this immediately and should notice it by the frame not being even on the top.
Fix: Just reopen the screen top, slide the screen frame top first in place, then close the rest of the case and test. Should be ok.