Battery replacement I phone 4
 

Hi, what is the best way to go ? Need a battery replacement...not a substandard one... Thank You

$80 through Apple.

No worry about substandard.

I'd look for a cheaper option.

Or find a quality source like non retail package OEM and tackle it yourself.

https://www.youtube.com/watch?v=KYvjuWg06l4

I get ones for my 3GS on ebay for about $7. Same as apple uses. A little tricky to install though.

This is a very easy job to do on your phone. Order a new battery on ebay that has the tools. You will need the pentalobe to remove the two screws near the charge port. the back cover will now slide up just a bit. lift it up and you can now see the battery. With the small Phillips screwdriver there is 1 screw holding the battery cable. don't lose the ground clip that's under the connector. Pry up along the edge of the battery to break it free of the adhesive holding it in. If you grab the plastic tab to remove the battery without prying first the tab will likely rip off. Then just put it back together. Make sure you power the phone off before you start and remove the sim card.