My question " after glass replacement, touch screen doesn't work" was not resolved until today. I've tried two other glass/digitizer replacements and both failed to yield any results. The third one works! Hurray! I spent more for the third one because the ad confirmed the original part # 821-0627-a. I bought three glass replacements from 3 different sellers, thinking that They were defective aftermarket parts. At the same time thinking that I destroyed the ipod by attempting this project. In the many attempts to get the first two to work,including plugging and unplugging, the ribbons acquired a very small tear. It would be tough to get my money back now that the ribbons are torn, even though they didn't work in the first place.
The only thing I did differently between the second and third glass was to plug in the headphones. Don't ask me what made me do that, but if it turns out that's what will affect yours, I need to know.
Hope this helps, I've been obsessed for several weeks with this issue.