Faulty Apple iphone SE M/head River area (windsor-maidenhead-freegle CGA SL6)

This a is faulty iphone, the battery has started to die on a regular basis, from a full charge to 10% very quickly, not sure if a battery can be replaced. There is a small crack by the start button but doesn’t interfere with the working, originally bought from new is unlocked & was replace last week. Will decide over the weekend where its new home will be.