@kishorpaswan since iFixit does not yet have a guide for this, use something like [link|https://www.youtube.com/watch?v=WFW55hq6_TQ|this video|new_window=true] to work on it. Let us know what you find while you have it apart. Check for any damaged components etc.
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. [link|https://ifixit.com/Guide/new|https://ifixit.com/Guide/new|new_window=true] The iFixit community will appreciate this.