Give me a couple of hours, I have the same machine on my bench with the same issue. I reinstalled the system and it would not fully boot. I have now reformatted the drive and attempting a clean install from and external drive. Will update you on my success. I am loading from a Sierra downloaded a week ago and not the current one (which I think may be the problem).
UPDATE
This worked. Reformatted the drive and did reinstall from external.
Customer appeared to have an incomplete installation. He was getting what looked like the start of a kernel panic. Disk Utilities found nothing. But disk was shown to be full and was actually only 1/4 full.A straight reinstall from an external source failed. I did drag and drop his documents, photos onto the external then restored them.
I just had to start all over with a fresh format and install and all is working now. Currently downloading purchased apps and iTunes update.
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