Hello Franco, Thank you so much, I revived flawlessly the m700 thanks to your dump !
The main cmos is the one just on the right on the picture above, the Winbond 26Q128F which has the right size for lenovos's bios binaries.
I had successfully updated the bios before on the Winbond one.
I tried a mod bios with the objective to get intel 7th gen support but it didn't work....

Sorry for the oversight
The serial is [B]PC0HWV0F[/B]Sorry for the oversight
The serial is [B]PC0HWV0F[/B]...

Hello,

I've this M700 tiny on which I had tried a modded bios to integrate intel 7th gen support (but it didn't work).
Then I made the terrible decision to revert back the bios with the backup at 10pm several months after, and accidentally erased the wrong cmos.
(The one right next to the cmos battery, which is a Macronix mx25L2006E and only 2MB in capacity.
The machine still boots but bios complaints about cpu fan error while it's blasting at full power (and damn noisy!), it also refuses to update the bios by itself.
Who knows what is the purpose of this CMOS...