Just got my factory voluntary upgrade FCU back and after getting it put back in the frame it will not fire. The magazine will fully seat so I don’t think it is that reassembly problem. It is the first time I have done this but everything functions except no click when the trigger is pulled. Mag drops freely, slide functions and locks back, trigger moves just no click. Any suggestions? Could’it be something I did or maybe an issue with the upgrade?

I believe there was another member who had this issue. IIRC, you need to either push up or down on the slide release while the slide is off. Then put the slide back on.

Try pushing one way on the slide release, reassemble and test. If that doesn't work, remove the slide, push the release the other way, reassemble and test.

This video may help. https://www.youtube.com/watch?v=esXcrADPYy0

Thanks I tried that but my mag will insert and seat fully so I don’t think that is it