UPDATE !!

I just want to inform you that my machine is now running on > 70 TH/s hashrate.

But before that, it was a long story that the point is I did return the hashboard for repair to the Bitmain HK repair center. It was done twice and spent so much money on it for the freight cost. Until I gave up returning the second replacement hashboard, because it gave the same error. I just let the machine run at 48 TH/s for more than a month, since I last returned. I guess the certain chip had broken within the replacement hashboard, or the PSU issue.

On Wednesday 16 February 2022, it was raining hard in the afternoon. Suddenly, a very loud lightning struck in the sky, made my computer monitor blips and the mining machine got an error in the Kernel Log. (But, the electricity was not blackout). I was really worried at that time, and did a restart on the machine as quick as possible. After restart, the 3 hashboards were all back to normal again. Especially the replacement hashboard (chain 2). At first, I was not believe the replacement hashboard can run again after more than a month inactive. But after more than 24 hours (several days, till now) run without error at all, I can assure the replacement hashboard is now working good.

I can't explain it technically, but believe it or not, the machine now runs at 70 TH/s (or up), and no problem at all till this time. Hope it can run normally for a very long time.

I'm happy now !!

Alhamdulillahi robbil 'aalamiin (All Glory be to Allah, Lord of the worlds).
Thank you guys for all your best support.

https://i.postimg.cc/68ZNhFYs/Hashrate-70-TH.png