Hello,
The default password of the bootrom menu is huawei or Admin@huawei.com.
If you can log in to the device through the console/telnet/ssh. you can use the reset boot password command to reset the password of the BootROM menu, as below.
<Quidway> reset boot password
The password used to enter the boot menu by clicking Ctrl+B will be restored to the default password, continue? [Y/N]y
Info: Succeeded in setting password of boot to "Admin@huawei.com".
If you cannot log in to the device or enter the BootROM menu, I'm afraid you'll have to return the equipment to the factory for repair.
By the way, if you want French support. You can visit our French forum directly.
https://forum.huawei.com/enterprise/fr/index.html
Let me know what else I can do for you!