I'm using an Arduino Uno board with an HP computer running Windows 10 and IDE version 1.6.8. Arduino was working fine for me until a few days ago, when (and I suspect this is the root of the problem) I accidentally tried to upload software with something connected to the RX and TX pins on the board. Now I continually get the error message below:
avrdude: ser_open(): can't open device "\.\COM2": Access is denied.
The only other thing that changed is I disconnected a bluetooth dongle (Kinivo BTD-400 Bluetooth 4.0 USB Adapter for Windows) without uninstalling any software, so I suspect that software may be searching for open COM ports and disrupting the Arduino upload.
I've tried everything I could find about troubleshooting online, including that "did I brick my arduino" post elsewhere on this forum, and nothing has worked or even changed the problem - please help! I believe I've narrowed down the problem to my computer scanning open COM ports, but I can't find any reliable way to make sure that doesn't happen.