Battery drain very fast how to solve..?

@amitojsing37926 first make sure that you are using the battery saver settings. to do that, you want to go into Settings ==> Battery ==> Power saving mode and turn it on.

Once that is active, the phone will automatically throttle performance and shut down background synchronization to stretch out your battery life. If you want to do this manually, stay in that same menu, select Default optimization, and you can toggle exactly which functions you want running and which ones you want to turn off.

If your battery is still draining rapidly after making these changes, you are most likely dealing with a bad battery that needs to be replaced. Since iFixit does not yet have a specific guide for that use something like this video Replacement batteries are readily available at many online stores.

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 issues with their device. 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!