You mean the water brake valve zero position sensor? It can be connected to RPM2, 3 or 4 if Freq 1 and 2 are used.

i got it work thxs .i have another question  i hooked up these see pic  to freq1 and 2 where do i hook up the water brake valve two

OK, disconnect and connect power again.

If you have connection again then click "Jump to bootloader". If that does not work, then your usb extension cable cannot be used during download. Connect directly to the PC with the supplied USB cable

If you cannot get connection, then open the box, hold the small button down while connecting power. The blue led will blink and the unit will be in bootloader mode and you can download. The usb extension cable (if used) may not be compatible. 

firmware upgrade failed

Does the download start? What is the error message?