Boot strapping a machine isn't impossible. It may be difficult but not impossible.
I boot strapped a IMSAI with a "DigitalSystems" disk drive and controller.
I'll admit I did know 8080 code but I had to start from scratch on the
disk controller.
No nice little WD controller chip to start with, just a 12X12 board to TTL.
I didn't even know it was a DMA device when I started.
I've trouble shot a 20 bit mini with no schematics.
A lisp machine would clearly be difficult but not impossible for a determined
hacker.
If it was designed to run it can be made to run again.
Dwight