I finally got an initial response from the service department of the Hong Kong distributor. They said they have tested the amp in their workshop for a few days, switching it on and off several times a day but failed to detect any abnormality.
Apparently this "cannot turn on again" problem does not happen all the time. I have actually taken a video of the problem last time when it happened in my home and sent it to them. So it is now stuck. I shall give them a few more days and demand a replacement or a refund.
Apparently this "cannot turn on again" problem does not happen all the time. I have actually taken a video of the problem last time when it happened in my home and sent it to them. So it is now stuck. I shall give them a few more days and demand a replacement or a refund.