UPDATE: After removin the RMM3 module, BIOS update was successful. Unfortunately, everything else fails (with or without RMM3 module).
BMC update shows "Unlocking front panel", then error message stating that front panel locking failed, because of communication error with BMC (the same with "BMC force update" enabled).
FRU&SDR update fails with error message about inability to read FW version from BMC.
ME update just fails with error 005.
Alert log shows error 84F2 (BMC failed to respond).
I'm affraid that BMC is dead.