it's basically the avrdude: stk500_getsync(): not in sync: resp=0x00 error.
a few days ago i might have inadvertently connected an external power source (8x1.2V = 9.6V) to the Nano power rail - not sure this can't be handled, but i am actually using a Nano clone from ITEAD Studios.
it uses the CP201x USB-to-TTL converter and i have tried re-installing the driver (for Win XP) but that didn't change anything.
several threads on this problem, mention possible problematic bootloader - so, i followed the "diagnostic tool" using Nick Gammon's code from this thread.
(i have an extra (original) Arduino Uno so was able to make the SPI-connections.)
and the result was;
Atmega chip detector.
Written by Nick Gammon.
Version 1.20
Compiled on Feb 3 2018 at 14:31:16 with Arduino IDE 105.
Attempting to enter ICSP programming mode ......................................................
Failed to enter programming mode. Double-check wiring!
Programming mode off.
i did a double-check, even trying the other RESET pin on the Nano and even connecting the jumper wires right up to the 5V and GND pins, instead of on the power rail, to which they are connected anyway.
i even tried the self-detect sketch from;
http://www.gammon.com.au/forum/?id=11633
but that resulted in a avrdude: stk500_getsync(): not in sync: resp=[b]0x30[/b] error.
i had tried that sketch on the Uno and it worked okay.
does this failure mean the Atmega is done for ?
or maybe just the CP201x chip ??
is there any chance of salvaging the Nano ?
)