EFI Boot freezes with 16 min left of install

Trying to install newer iOS on a Mid-2012 iMac. I have created 3 different EFI boots using the OCLP instructions from Mr. Macintosh and I always get stuck with 16 minutes left of the install. I’ve tried different USBs, different OS (Monterey, Big Sur, Catalina) with no luck. Any suggestions?