5 - 30 minutes
It was a mess and probably not worth fixing, but I had fun doing the repair and got it right the second time. Haha.
Got all the parts back in place and this time it worked, even the speaker. So, what's that little wire from the speaker to the main board for? It doesn't come with the speaker, so that was a loss. The little connector end had come off, but I guess just squeezing it back into place worked.
Take your time. Get it right the first time.
iPhone 4 Replacement Battery
iPhone 4 (GSM/AT&T) LCD Screen and Digitizer
iPhone 4 and 4S Speaker Enclosure