sep_rom — Secure Enclave
The Secure Enclave cannot boot from its ROM: the associated memory chip or its link to the CPU is damaged. This data is unique to the device and cannot be rebuilt.
iPhone
SEP ROM chip/line (EEPROM) or its link to the CPU — logic board
Medium confidenceVerified sourceSecure Enclave
First check
Logic board diagnosis (CPU↔EEPROM lines).