You shouldn’t need to change that.
I think the rx/tx pins are on even if it doesn’t have 12V power. Maybe sure it lights up without the USB. The 12V powers the cpu and the usb can’t.
Other than that, make sure you have the right port.
COM3 (RAMBO) selected.
I’m clueless.
Unplug the USB and see if you still get lights. Your error is most commonly no power, there are two fuses on the board and if you used the adapter it has a bad connection for some.
The power LED has always remained constant. Those rx/tx LED’s only seem to flash intermittently when I send the arduino sketch over the USB connection.
I have tried sending this over my laptop but the same problem occurs.
I don’t understand, I’ve put the marlin firmware on it before and ran jobs over the exact same connections.
Is it time to buy a new board and scrap this one?
Nope.
The only reason I see at this point is maybe one of fuses blew or your power supply is not getting power to the board. Verify all three fuses by taking them out of the board and testing, you can not test them in the board. Also verify you are getting 12v to the board.
Tested them with a multimeter. All 3 fuses are fine and the power supply is reading 12V.
I know there is nothing wrong with the power supply.
What version of the firmware are you trying now? This thread is showing two different screens and is 3+ years old. Would you mind doing a post showing exactly what we are trying to do here and what hardware you have.