[SOLVED] Black screen on e6420 Sierra upgrade

[someitalian123]

Update, I got everything working, I used the El Capitan DSDT for A22, with the Sierra config-LowRes from the new bootpack, then I made sure my AppleHDA was vanilla by replacing it with one I extracted from the InstallESD.dmg for Sierra. Then I reinstalled the AppleHDAIDT in /Library/Extensions and I re-ran the permission script a couple of times. Both audio and video work now, thank you.