"Like most phones, the H3 won’t power on without a battery connected"
Instead of a battery, I often use a constant voltage constant current 3.7V SMPS regulator board to switch on my old phones when I want to experiment with them. Connect the positive lead, ground the other two leads, and most of them (i.e., 7 out of 8) turn on just fine.
Instead of a battery, I often use a constant voltage constant current 3.7V SMPS regulator board to switch on my old phones when I want to experiment with them. Connect the positive lead, ground the other two leads, and most of them (i.e., 7 out of 8) turn on just fine.