Koepi:
The new board description was for Nano with Optiboot. There is an Optiboot loader for the Nano in the Arduino.app archive which I used in one of my attempts. But to use this variant I'd need to add a different board type as this is obviously nothing official.It doesn't matter which ATmega328 bootloader I choose. Flashing with USBasp makes the board work (while being attached to USBasp). If I remove USBasp and plug in the Nano the usual way, it plays dead. You can see that very easy when using a blink sample: Freshly flashed, it blinks; plugged in the usual way only power LED is on.
But the standard Uno optiboot loader works fine in the nano, no need to install from any other version, that was my point.
Sounds like a defective USB FTDI serial interface chip. Does the PC see and 'ding' when plugged into the PC? If not it's defective, if it does then perform the serial loop back test (there is a sticky around here somewhere) to see if serial data is possible.