The first time I tried this, I bricked my phone, and had to sell it for scrap. It works fine as long as you do everything very carefully. Also, it's helpful to test the battery for +3.7V before taking the phone apart. Lithium batteries can't run to 0, or they're good for nothing but a paperweight. One tip is to run your fingernail along the margin between the screen and case to remove stuck dirt which inevitably ends up there. Don't use a spudger and definitely don't use anything metal. It's way too easy to scratch or damager something. Clean margin will make the screen removal way easier. My phone is now working fine, although I only use it now for a portable music player and ooma client. Well worth the $6.50 I spent on a new battery.