Hi Gutemine, thank you for your reply.
I had checked and could not find the latest log except 1 that is dated 3rd Aug 2019 in the harddisk. Moreover everything in root is new as I had to do a new flashed because it could be switch-on at all. I am afraid I will not be able to produce a log if this happen again because I do not know the way to log-in. I had tried to login from browser, Ftp, Samba, Dcc-e2, none is possible. Please advise on how to obtain a log if this happen again? Or any other thing that I should take note of? Best Regards