Unable to flash anything, fastboot reports status OKAY but does nothing

Hi everyone,

I have a Samsung Galaxy Nexus and I'm trying to flash the stock ROM from Google. The problem is that whenever I try to flash something via fastboot, it all seems good, everything return OKAY, but then nothing changes. Not even a new recovery can be flashed this way.
It is the same when I try to flash an image using the recovery TWRP.
This behaviour is exactly as described here and here.

Any idea what can I do to regain back the ability to flash anything to the phone?

==================================================

The procedure I'm following, from the script Google itself provides in its Android image, is:

1. Turn on in fastboot mode (bootloader)


2. fastboot flash bootloader bootloader-maguro-primemd04.img


3. fastboot flash radio radio-maguro-i9250xxlj1.img


4. fastboot reboot-bootloader


5. fastboot -w update image-yakju-jwr66y.zip

but it remains the same with every other ROM, including Cyanogenmod 11.

The phone is a Samsung Galaxy Nexus - not Verizon, not Sprint - equipped with:

• ROM: Cyanogenmod 12.1 UNOFFICIAL


• recovery: TWRP 2.8.6.0


• bootloader: unlocked