Arduino UNO is not working, L led is always on. Please help me!

Projects General Guidance
1

Hi,
My arduino UNO is not working, the L led is always on and my laptop not foud arduino.
I try switch port, but Arduino isn't found.
I verify the cable and he doesn't problem.
Please help my.

2

That's not good. It might be broken.
Do you have a multimeter to measure the 5V pin ?

Did you do something with 12V ? or did you use a programmer ?

3

On my Uno the L led is always on unless I press the reset button or open the serial connection on the PC. (That is, when I have no Arduino code to switch the LED off).

Does you LED flash when you press the reset button? If it does I suspect the Arduino is OK.

What operating system have you on your PC?

...R