Before seeing this error I did a project with my Uno board using a Bluetooth module.

After that, when I powered the board to upload another program, 4 LEDs (L, TX, RX, ON) went red without blinking.

So now, every time when I power up my Uno board, without any connection with any of the pins previously mentioned, the 4 LEDs are red coloured all the time.

  • are you able to upload something, like a "blink" sketch to board ? Mar 23, 2020 at 20:44
  • There may be good reasons, that the LEDs are on. That's not directly an error. Are you still able to upload programs? What happens, if you upload the blink example?
    – chrisl
    Mar 23, 2020 at 21:01
  • When I tried uploade the blink example it's not uploading to the board,it says there a touble shooting problem.
    – Brown
    Mar 24, 2020 at 4:28
  • Please give us the full error message (add it to your question by editing it)
    – chrisl
    Mar 24, 2020 at 8:21
  • If the LEDs are red then it's not a genuine Arduino. If it's not a genuine Arduino then all bets are off as to what happened.
    – Majenko
    Mar 24, 2020 at 11:17

1 Answer 1


If you can upload sketches, I don't think it is that big of a deal but if you can't, check the TX and RX pin tracks since if those tracks are shorted, they can keep the indicator lights on for ever due to the Serial code on the Arduino. To get further help, please tell me what happens if you try uploading code.

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