arduino uno smd r2: avrdude: stk500_getsync(): not in sync: resp=0x00

Hi sp computing
I used my functioning Uno smd and uploaded the sketch. No error message.
I connected both boards as discribed with separate wires.
The defective board:

  • shows the green power LED on.
  • shows the LED 13 blinking identical to the programmer board. (ah! it ain't broken!)

I open the serial monitor and adjust to 115200 baud.
I hit reset on the programmer board.
The monitor shows:
Atmega chip programmer.
Written by Nick Gammon.

That's it, no further question.

I sent "U", nothing.
I sent "G", nothing.

What I am doing wrong?