Save your time and protect your computer. The era of custom IPSW files for iCloud unlocking ended with the introduction of the Secure Enclave and APTicket in 2013.
Modern iPhones use a dedicated hardware chip (the Secure Enclave) that handles encryption and authentication independently of the main OS. Firmware Signing: custom ipsw icloud unlock top
On : Hold the Option/Alt key and click "Restore" or "Check for Update". Save your time and protect your computer