Connectcore 6UL can't reboot but can work by Power on

We use Connectcore 6UL
We find that the board can work after Power on.
But when type “reboot” under console (linux system) ,only display “Rebooting…”
Under uboot system type “reset” under console ,only display " resetting…"
Can give some information about this question ?
Hardware or Software ?

please program stock images via the procedure described here

This will reprogram u-boot and reset env to defaults.
Also does reboot command from u-boot work?
If this fails, open a support ticket to RMA the board.

Problem Solved
N20 pin can’t be used as ENET_PWR control
We changed it,everything is ok