« on: October 17, 2016, 08:56:49 am »
The debug file only confirms what you are describing, that FM is not getting a response.
Please go back to your terminal approach. Eight bits, no parity, one stop bit (aka 8N1), 19200 baud. Send a single '?'. It should be echoed back but you will find that it isn't.
Put a scope on the RxD pin and check the '?' is arriving. Put a scope on the TxD pin and check if it is being transmitted.
Put a scope on the XTAL pins and check for a waveform. Double check supply voltages, make sure no noise or ripple. Also the reset line. Double-check the voltage at the ISP entry pin and make sure that when you are resetting the part the voltage is going down to zero at the pin.
Most likely cause is electrical - either a bad solder joint or incorrect design.