Latitude E7240 : unable to update bios, I tried all methods and all versions

Hi.

The laptop has A09 bios version

I run the E7240A29.exe to update the bios with it.

It shows me the current version A09 and the next A29.

I validate.

The progress bar goes to the end and the laptop reboots.

I check and the version is always A09

I tried first to update to A29 with no success

I tried with : E7240A10.exe, no success.

I tried all updates :

E7240A10.exe
E7240A12.exe
E7240A13.exe
E7240A14.exe
E7240A15.exe
E7240A16.exe
E7240A17.exe
E7240A18.exe

E7240A20.exe
E7240A21.exe
E7240A22.exe
E7240A25.exe
E7240A27.exe
E7240A28.exe

E7240A29.exe

The laptop has the same behavior and I always get the same result : no update.

I tried what I saw on the support site :

unplug the AC cable, press CTRL + ESC, plug the AC cable and press CTRL + ESC : no effect.

The laptop starts normally.

Thank you for your help.