@Happy Bhakti I haven’t done this repair yet, but have been reading all the comments. You can leave the display attached. Here is a comment I saved:

I found it wasn’t necessary to detach the screen at the top. Rubberband the screen at a 90 degree angle to a small box or something similar (see the illustration in step 13). Then you can skip steps 17-22! This prevents accidentally messing up the cables at the top of the phone, or putting the wrong screws in the wrong holes.