Error uploading sketch, please help!

Ok so I have spent three days trying to connect my crius se 2.5 board and searched for hours on here for an answer to no avail. When I try to upload the sketch i get the following error:

avrdude: ser_open(): can't open device "\.\COM1": Access is denied.

I have tried changing the com ports, uninstalling/reinstalling, rebooting.... I am lost and quite frustrated. Any help would be greatly appreciated!

I am running this board on a quad x multicopter My OS is Windows 10

Crius SE 2.5 MultiWii Flight Controller (HCRECO0001) I guess?

No idea. How did you connect it to the PC?

The above link is for a forum; maybe register there and ask the question.

I am connecting via FTDI