I’ve had issues with my iPhone 4S for quite some time now. I’ve been patient long enough using a power bank but it came to a point that it annoyed me, it doesn’t hold the charge anymore. I finally decided to get the internal battery replaced.
With the help of a friend (Gerard Van Schip), he convinced me that I can just get the parts online and do it myself rather than spending more on servicing. I went ahead and ordered the parts (battery and pentalobe screwdriver) from Tmart. It took a while before it reached me. Tmart’s prices are dirt cheap but shipment takes a while probably because of overwhelming orders.The tutorial is from iFixit, it’s straightforward and easy to follow.