I have use the manual process.
1- I have write the minimal image on the sdcard with :
$> xzcat Fedora-Minimal-armhfp-21-5-sda.raw.xz | sudo dd of=$MEDIA; sync
2- I have write the uboot.imx file from the /usr/share/uboot/wandboard_quad/ of the just writed sdcard with :
$> sudo dd if=path/u-boot.imx of=/dev/mymdia bs=1k seek=1 conv=fsync; sync
I think I have tried 2 times, but if other people have tested with succeed, I whould have to test again.
But it's probably me who made a mistake.
PS: If it can change something, I have a wandboard quad "rev C1".