Hi Guys, I need your help because my phone is unbootable after I finished the following steps in X-Terminal:

1, apt-get update.
2, apt-get upgrade.
3, reboot

Anyone knows how to fix it? Thanks in advance.

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How strange it is that my phone can boot now! I have done nothing at all. When I choose the V51 option in multi-boot menu the phone can not boot. When I close keyboard and start the phone it successfully boot into V51. I am curious about the reason.