Hello,
I believe you're trying to flash an NXP EVK, right?
Please check that there is an eMMC populated in the SOM board, this because uuu.auto script is used to flash uboot and rootfs into eMMC.
If there is a populated eMMC, please share your uboot log, usually it will show an error message.
If not, please try with the following command, it will let yous flash a Linux image (uboot & rootfs) into a uSD card:
$ sudo ./uuu -v -b sd_all u-boot-imx6ulz14x14evk_sd.imx fsl-image-validation-imx-imx6ulz14x14evk.sdcard
Note: For this you'll need to have a uSD card inserted into the corresponding socket.
Also, if there is no particular reason for the use of L4.14.62 I'll recommend to use a GA version since it is more stable than a beta image, you may find the demo files here:
https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applicat...
Note: UUU is supported in L4.9.123 and later.
Hope this helps,
Best regards,
Aldo.