Arduino Yun: Problem uploading sketch to the board

I've got few Yuns to play with. It's a nice piece of hardware with 2 CPU's one of which is responsible for running Arduino code and the other one adds wifi connectivity to the board and runs modified version of OpenWrt (great!).

So configuration of the board was pretty straightforward. Same with the OpenWrt upgrade. However, when it came to uploading my sketch to the board from Arduino IDE I've got the following error:

avrdude: ser_open(): can't open device "/dev/ttyACM0": Device or resource busy avrdude: ser_send(): write error: Bad file descriptor Problem uploading to board. Seehttp://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

I've also noticed that right after the failed sketch upload, the IDE was showing that the device was now connected to the other port (incremented by one), like /dev/ttyACM0 before and /dev/ttyACM1 after. So if I would ls /dev/ttyACM* I'd get something like this:

lsusb command also showed weird output. Arduino was detected but not properly recognized.

Clearly there was some problem with the bootloader of the device. So before trying to restore it I decided to try one more thing: uploading the sketch via wifi (Arduino IDE automatically detects the device if your computer is on the same network). So I gave it a try and it worked! Moreover, afterwards I could upload a sketch through the serial connection (micro USB).

When uploading through the wifi Arduino IDE displayed the message that something was wrong with the flash memory and it was going to fix it. Well, I guess it did, 'cause afterwards everything worked as it should have.

So in short, try to upload a sketch through wifi.