@RichieRich ,
I may find an issue with one of the batteries (the blue one in the above pic). I was trying to charge it with 4S 14.8v, 3.3A settings, but the charger tells that the blue one is recognized as only 3S and breaks the charging every time. It's quite weird why the charger tests the battery as a 3S setting. The green one works well, and no CPU error happened after fully charging.
So, I think I may have to contact the battery provider to double-check the quality of the blue one. Since the blue one cannot charge at the time, I may not be able to test this error with logs. I will get back if the battery provider could advise me how to charge it.