Latley I have burned out 2 nano boards. Both were loaded with a simple 10 channel 5mm led flashing sequence program (560 ohm resistors for each). Powered by a small 5aH 12v battery . They both seemed to just die all of a sudden. The one that died today had the pwr, tx and rx light on steady and reset did nothing , the AT chip was super hot. It had been working flawlessly as a cool power indicator for months.
I've heard mixed info on power input for nano's. Some say 5-16 volts is no problem, others say never go over 5v regardless of the spec sheet. I'm going to start adding an L7805 regulator to every one from now on but was it the 12 volts causing the premature death on these boards or what?