My phone screen get pink colored it spread rapidly over the screen

@honoured going by your description, you have a broken LCD. You will have to replace it. Use something like this video or if you can get a display with the midframe use these instructions They are written in French but browsers like Chrome etc. provide a pretty good translation.

Replacement displays are readily available and not to costly. Just do an online search and make sure that you get a display that is for your version. There are quiet a few different once SM-A305F/DS (Global); SM-A305FN/DS (Europe); SM-A305G/DS (LATAM); SM-A305GT/DS (Brazil); SM-A305GN/DS (APAC); SM-A305YN (AU/NZ) and you always want to make sure that you check for compatibility.

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. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!