This is WIP, may contain incomplete info.
You need to find 13.2_17B45a_InternalUI_D331pAP_DVT, sha256sum ffdc84e560e14cad79916aaa9f143b225348ebca47e8fdd096a7cd47bdd0983d on the internet. I can't include the link here.
Copy all IMG4 files from the dump /usr/standalone/firmware/* (and inside FUD too) to your working dir.
Make 2 volumes from ramdisk, I have my System and Data as disk0s1s11 and disk0s1s12, mounted to /mnt1 and /mnt2 respectively.