Well, I see someone else has been bitten by the latest EDP.
There's a problem here guys.
I had long ago over-written the myHack USB stick I used for install. Building a new one using either of the D620 bootpacks results in the same fail.
Fortunately, I was able to build a workable USB boot stick using the Extra folder from this post, plus the DSDT from the one of the latest D620 boot packs.
Therefore, the DSDT is not the problem. I also tested the smbios.plist and org.chameleon.Boot.plist, and they weren't the problem either. So I suspect either Extensions/ or modules/