How To Easily Remove, Install & Replace an Apple iPhone 4S Battery - YouTube
Fon ☃️ on Twitter: "old iPhone 5 laying around 📱 - replaced battery had to use hair dryer to help remove old battery - upgraded to iOS 10.3.4 using iTunes on PC
How to Easily Replace an iPhone 4 Battery - YouTube
Use Low Power Mode to save battery life on your iPhone or iPad - Apple Support
Top 10 Settings to Change on Your iPhone 4S
Apple admits slowing older iPhones because of ageing batteries | Apple | The Guardian