Oh this is great information! Let me do the tests you suggested. I really do wonder if one of the cells is faulty or something's wrong with the board connection. I'll check.
I noticed sometimes when I plug in the first battery, a green light will flash briefly on the board. But not the second battery. I thought it was designed to do it with just initial power. But other times I remember the first battery not flashing but the second would. Are they both supposed to flash?
I noticed sometimes when I plug in the first battery, a green light will flash briefly on the board. But not the second battery. I thought it was designed to do it with just initial power. But other times I remember the first battery not flashing but the second would. Are they both supposed to flash?