I'd been keeping the phone to keep vm's of my Mom (who has passed), phone started flaking (dying), got new battery to give one last try at getting contacts and data (even recording it from 3GS to another device).
I got the kit (with all the special tools...which were very handy). I was able to get the battery out with tutorial, but not back in properly. The tutorial walks you through getting the battery out and back in, but not putting everything back together. Logic board was hard to get in straight to allow for the SIM Card to go back in. I had to take it to a Gadget Patcher, who quickly fixed. Phone has been working fine since, though we lost the VMs??? I've been able to get the other data.
The Gadget Patcher highly recommended IFIXIT too.