# Arduino Cloud won't connect to UNO R3, L LED no longer lights

**URL:** <https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334>\
**Category:** UNO R3\
**Created:** [November 4, 2025, 9:28pm UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334 "2025-11-04T21:28:59Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![elegoo\_arduino\_uno\_r3\_ben](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/elegoo_arduino_uno_r3_ben/32/1098795_2.png) [@elegoo\_arduino\_uno\_r3\_ben](https://forum.arduino.cc/u/elegoo_arduino_uno_r3_ben)\
**Post date:** [November 4, 2025, 9:28pm UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334/1 "2025-11-04T21:28:59Z")

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Continuing the discussion from [L Light Does Not Light Up](https://forum.arduino.cc/t/l-light-does-not-light-up/1403091):

I'm having a similar problem - I have an Elegoo Arduino Super Starter Kit and when I unboxed it everything was ok and mostly functional. I have two problems: the first has always happened ever since I got the kit, and it is that the arduino cloud editor refuses to connect to my board (an Arduino Uno R3), and the second, which started a couple months ago, is that, after experimenting, my board's L LED no longer lights, not even when I press the button. I'm not sure if I burned out the led, because I plugged it into slightly higher power than normal at one point, but the power LED is fine. Can someone tell me how to fix this because my parents will kill me if I have to return or replace it 💀  
Oh, also, the serial numbers on my chip are: 35473D ATMEGA328p U 24030G2

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**Author:** ![JCA34F](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/jca34f/32/340148_2.png) [@JCA34F](https://forum.arduino.cc/u/JCA34F)\
**Post date:** [November 4, 2025, 9:46pm UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334/2 "2025-11-04T21:46:05Z")

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Disconnect everything from UNO, run this program

```arduino
void setup ()
{
  pinMode (LED_BUILTIN,OUTPUT);
  digitalWrite (LED_BUILTIN,HIGH);
}

void loop()
{
}

```

Does the L led come on?

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<div class="post-metadata">

**Author:** ![JCA34F](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/jca34f/32/340148_2.png) [@JCA34F](https://forum.arduino.cc/u/JCA34F)\
**Post date:** [November 4, 2025, 10:09pm UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334/3 "2025-11-04T22:09:46Z")

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> [@elegoo\_arduino\_uno\_r3\_ben](#):
>
> I'm not sure if I burned out the led, because I plugged **it** into slightly higher power than normal

What is **IT**? What was the voltage of "slightly higher power than normal"?

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**Author:** ![xfpd](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/xfpd/32/1120236_2.png) [@xfpd](https://forum.arduino.cc/u/xfpd)\
**Post date:** [November 5, 2025, 12:27am UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334/4 "2025-11-05T00:27:35Z")

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> [@elegoo\_arduino\_uno\_r3\_ben](#):
>
> the arduino cloud editor refuses to connect to my board

Do you have the Agent (software) installed?

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/6/7/f/67f98ff53a1f59f9e268d3cea642469a8e57824f.png)

> [@elegoo\_arduino\_uno\_r3\_ben](#):
>
> L LED no longer lights, not even when I press the button

Does the "L" LED light as you plug the Arduino into USB or stand-alone power and does the Arduino Power LED light?

Do you hear your computer operating system "chime" when you plug the Arduino into the USB port?

Arduino have a troubleshooting page:

[https://support.arduino.cc/hc/en-us/articles/360014869820-Install-the-Arduino-Cloud-Agent](https://support.arduino.cc/hc/en-us/articles/360014869820-Install-the-Arduino-Cloud-Agent)

Also, if you have a non-OEM-Arduino, you will get this... (with a warning at the bottom)

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/2/a/4/2a44d43685d0ee4762ebbadd6ad95a7cdb71e78b.png)

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/5/9/d/59df1385535d25539489853f5ccbfa99b5b8e6d0.png)  
(but the "continue" button does not proceed to the "configure" page)

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**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [May 4, 2026, 12:28am UTC](https://forum.arduino.cc/t/arduino-cloud-wont-connect-to-uno-r3-l-led-no-longer-lights/1412334/5 "2026-05-04T00:28:35Z")

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