Did I brick my uno in the first 30 sec?

Using Linux I plugged in my uno and it seemed to recognize it. Assigned it a serial port and I could click board info and it would tell me serial number and stuff. Then I clicked the upload to ardunio button with whatever the default blank sketch is when you open the software (just trying to verify good connectivity). After that I can't get it to connect to the pc again. Dmesg command shows nothing when I plug and unplug USB. Testing from a windows machine I get nothing when I plug it in. No new hardware, and nothing in device manager. When I power up the uno I get 1 very fast flash of the L led and then green on led steady. I think before it stopped working in had 3 slow blinks of the L led but I'm not sure.

linuxrunner:
... I think before it stopped working in had 3 slow blinks of the L led but I'm not sure.

3 fast blinks, isn't it? Arduino runs the bootloader first, after reset. The bootloader flashes L 3x fast. Now it looks like the bootloader is missing but in addition there is the problem with USB/serial tranceiver (smaller chip near to USB).
Is your Arduino UNO original or some clone?
Try another computer and USB cable, just to be sure it is a problem with UNO board.

Yeah from searching it sounded like the bootloader is messed up but I didn't realize that it should still be connecting via USB serial with a bad bootloader. I'll try a new USB cable

okay i tried a new USB cable after not touching it all night and it worked, connected right up. :slight_smile: i then attempted to follow this tutorial ( 16×2 I2C LiquidCrystal Display(LCD) « osoyoo.com )for hooking up a LCD and once i got the LCD attached as outlined in the tutorial i attempted to plug the usb back into the PC to power back up the arduino and it won't connect again (even with the new cable). i also attempted to do this yesterday (hook up the lcd) before i noticed that it no longer connected to the PC.

The LCD screen lights up and seems to work but even if i disconnect everything from the uno it still won't connect to the PC. i am going to wait overnight and try it again tomorrow.

the arduino is a clone by osoyoo

Once you have it working, try to upload some sketches that don’t require additional hardware. Use a variation of blink with a different delay, use a sketch that communicates over the serial port.

If that works, connect the lcd. If you get problems (can’t upload), there is more than likely something wrong with the lcd.

I seem to recall that some of the I2C lcd modules have a poorly designed hardware; wished that I could find the links back.

Some of the older serial modules are a pita.
I have an adafruit one here that insists on using pins 0 and 1 and we know that method is not going to work too well to start.

Ballscrewbob:
Some of the older serial modules are a pita.
I have an adafruit one here that insists on using pins 0 and 1 and we know that method is not going to work too well to start.

It's I2C :wink:

it's definitely bad hardware, something with the uno. I found that if I put it in the fridge it will work until it warms up at that point it no longer connects to the PC. must be a bad connection somewhere I have a replacement being sent to me.

Thanks for all the help with this one.