[Arduino Yun][UBoot][Brick]after erase UBoot, is any method can recovery it?

Hi Experts,

There is an accident, I erase the UBoot and forget to recovery it (copy back),
now my Arduino Yun cannot access through WIFI or LAN and cannot enter UBoot promote.
Is any method can recovery my UBoot in this case?

Thanks a lot,
Pochun

this might help you