Hi.
I have an Arduino Uno that I have been using for a while now, but today something have happened and I can't upload to it. The IDE sais:
"avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x20"
on the last error line.
I have noticed my computer doesn't make any sound when connecting the board anymore, it did before.
I'm kind if new to Arduino so I would really appriciate a little help. Thank you
Anyone?
My suggestions
1 try a new USB cable
2 connect to a different USB port on your computer
3 connect the UNO to a different computer and see if it appears in device mgr
4 check out the troubleshooting guide and loopback test which are mentioned in the pinned posts at the top of the forum
5 it is possible you may need to reflash the USB-to-serial chip on your UNO using DFU or ISP programming if it won't connect to any computer with any cable
dmjlambert:
My suggestions
1 try a new USB cable
2 connect to a different USB port on your computer
3 connect the UNO to a different computer and see if it appears in device mgr
4 check out the troubleshooting guide and loopback test which are mentioned in the pinned posts at the top of the forum
5 it is possible you may need to reflash the USB-to-serial chip on your UNO using DFU or ISP programming if it won't connect to any computer with any cable
Thank you for the answer.
Step 1 & 2 I have tried without any results, I shall take a look at 3 & 4.
Reflash with DFU and ISP programming, this sounds hopeful after googling it. But I can't really understand how it works. As I understands it is possible to "reflash" the 16U2 chip with another arduino? I found a guide here: https://www.arduino.cc/en/Hacking/Upgrading16U2Due
, but this seems to be for an Arduino Due. I have access to an non-official Uno if that could help me? The broken one is a Uno R3, could be worth to mention maybe.
Thanks again
It's hard for me to search since I don't really know what I'm searching for 
I have noticed this chip gets really hot after a few seconds of power to the board, don't know if I dare to connect it anymore? Started the Loop-back test when noticed it, I didn't do the test to the end therefore.
Hmm if it was getting hot during loopback test that makes me think you didn't get the loop back test jumpers connected to the correct pins.
Verify it stays cool with no pins jumpered and just skip the loopback test for now.
After doing #3 to verify problem is not with your computer, next step would be #5 and that is easiest with your clone Uno as an ISP programmer:
http://m.instructables.com/id/How-to-Restore-the-Arduino-UNO-R3-ATmega16U2-Firmw/
dmjlambert:
Hmm if it was getting hot during loopback test that makes me think you didn't get the loop back test jumpers connected to the correct pins.Verify it stays cool with no pins jumpered and just skip the loopback test for now.
After doing #3 to verify problem is not with your computer, next step would be #5 and that is easiest with your clone Uno as an ISP programmer:
http://m.instructables.com/id/How-to-Restore-the-Arduino-UNO-R3-ATmega16U2-Firmw/
It gets hot even with nothing connected. I have tested to connect it to another computer now with the same result, nothing. It seems to get power but it's still not detected by any computer. I would like to test #5 but I don't understand the guide, it feels like just information to me without steps 
That is bad news. That part could be defective or damaged because of a short currently somewhere on the board, or a short or overload has occurred on your board in the past. To fix it would require hardware skills I don't yet have, so somebody else on the forum could provide better guidance. Considering clone Uno's cost about $6 to $10 USD, I probably wouldn't spend much money or time on replacing parts.
Accelgronvall, Also check the voltages with a multimeter.
My computer started doing the same thing. Try step #7 in this link.
http://forum.arduino.cc/index.php?topic=328569.0
if link doesn't work here is the message:
All, I re-programmed the ATMega16U2 using:
the latest FLIP (FLIP 3.4.7 for Windows (Java Runtime Environement included)) from ATMEL
--- http://www.atmel.com/tools/FLIP.aspx ---
Then HEX file :UNO-dfu_and_usbserial_combined.hex
Then unplugged and plugged the UNO board back in, New device was found, then pointed to the latest Arduino driver, and ....
I am back in business
dmjlambert:
That is bad news. That part could be defective or damaged because of a short currently somewhere on the board, or a short or overload has occurred on your board in the past. To fix it would require hardware skills I don't yet have, so somebody else on the forum could provide better guidance. Considering clone Uno's cost about $6 to $10 USD, I probably wouldn't spend much money or time on replacing parts.
Yes I was afraid that was the case. Since I have a clone Uno that works just as good it's no catastrophe if I don't get it to work. I can allways buy another clone. Thank you.
CH701Builder:
Accelgronvall, Also check the voltages with a multimeter.My computer started doing the same thing. Try step #7 in this link.
Arduino UNO R3 USB stopped being detected with Windows XPSP3 - IDE 1.x - Arduino Forum
if link doesn't work here is the message:
All, I re-programmed the ATMega16U2 using:
the latest FLIP (FLIP 3.4.7 for Windows (Java Runtime Environement included)) from ATMEL
--- http://www.atmel.com/tools/FLIP.aspx ---Then HEX file :UNO-dfu_and_usbserial_combined.hex
Then unplugged and plugged the UNO board back in, New device was found, then pointed to the latest Arduino driver, and ....
I am back in business
Okay I will check with a multimeter. But first I will try the steps you posted, since I don't have a multimeter at home. Thank you very much and also for the link.