I am posting this reluctantly, but nothing I've tried has worked. I need some new ideas.
About a month ago I was slinging some code, passing parameters by memory (not a good idea) and I 'broke' one of my Nano's.
It's a xinda Nano V3.0 (Arduino-compatible), and I've broken this one previously by shorting 5V and GND on a breadboard and blowing the Schottky diode D1. I was able to replace the diode successfully and it's been working fine.
This time, on power-up the 'L' (d13) LED blinks quite fast (maybe 10Hz?) and the IDE (1.0.5 under openSUSE 12.3 on my Dell Inspiron 6400 laptop) says:
avrdude: stk500_recv(): programmer is not responding
If I jumper TXD to RXD, I can echo whatever I type in the terminal.
My other (identical) Nano works fine, as does my Uno, so that leaves out cables, drivers, etc. It's this particular board.
I've come to believe (can't prove it) that its the bootloader that's flashing the LED, since the last sketch successfully "uploaded" (shouldn't that really be downloaded?) doesn't touch d13.
Googling gets me unsolved cases and the troubleshooting pages here, neither of which has helped.
I have also verified the bootloader with Nick Gammon's very excellent Atmega_Board_Detector running on my Uno and wired up via ICSP. The results match my working Nano.
I'd like to fix it. I'd like to learn what I did wrong and avoid that (like I'm now powering down before fiddling with jumpers on breadboards!).
My best guess right now is that RXD (or TXD) pin on the ATmega328p is fried. If so, that won't be worth fixing...
Any other ideas or suggestions?
PS: is it possible to write a sketch that "breaks" an Arduino?