here the answer from the support
it seams there is no recovery function at all
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Dear Roland,
To flash BMC, you should do it under WebUI.
From your description, it is possible flashed the wrong firmware and caused firmware crush. If the previous firmware you updated was 4xx / 8xx, then you will need to flash the firmware with the same series. If the system is still able to boot up, please flash firmware again with rootpath utility\fwud\dos which is in firmware file. Please use a bootable DOS pen drive and flash firmware under DOS mode.
However, if the problem still remains, then please contact your supplier (where you bought this product) for arrange the repair service.
Regards,
GIGABYTE