When your iPhone shuts off by itself, if the battery drains faster, or if your iPhone refuses to charge, then it a time to change the battery. Cell N Comp Repairs use a brand new 0-meter premium battery, and it comes with 30 days warranty. You can extend the life of your iPhone battery by not charging the phone for a long time after you charge 90% or 100% use the battery, and once it drops to 20% or less than that, you can charge again. Most of the stores used refurbished battery which is in poor health.
Giving priority to battery health is very important. When the battery health is good, then the health of your iPhone will be good. If the battery has poor health, then unexpected shut-off may occur, which may affect the mainboard.
All Repairs get 30 days part and labor warranty unless there is no physical damage or water damage.
When the battery is bad, it doesn't allow the battery to charge.
When the battery is bad it will start draining fast.
This happens due to defect battery.