The combination firmware is only a tool. The phone won't work normally until stock firmware is restored.
| Error Message | Cause | Solution | |---------------|-------|----------| | Protocol Error. U8 not supported. | Z3X version older than 24.1. | Update Z3X to the latest version (check "Support U8" in changelog). | | NV Rebuild Failed. MD5 Mismatch. | Combination file not matching U8 version. | Re-download U8 combination file. The bootloader must match: G930FXX**U8** . | | KERNEL LOCK – SECURE CHECK FAIL | You forgot to flash combination firmware first. | Re-flash combination file, then repair in Download Mode without rebooting to system. | | Unknown modem error – Shannon 335 | Exynos modem firmware corrupted. | Use Z3X “Write Modem” function with extracted modem.bin from stock U8 firmware. |