@honeysingh38432 I assume that what you are not saying is that it does not work when it is not plugged in to charge. In that case, replace the battery and re-evaluate after. While you replace your battery, check the charging board and the flex cable connecting the charging board to the main board. Make sure it is seated properly and has no tears etc.
Since iFixit does not yet have a specific guide for this task, use the one [https://www.nadiemellamagallina.com/en/manuales/smartphones-1/xiaomi-191/xiaomi-redmi-7-1099/bater-a-9650|from here] It was written in Spanish so use a web browser that does the translating for you, if needed.
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 a device with the same issues 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!