https://askubuntu.com/questions/98702/how-to-unblock-something-listed-in-rfkill

You have to blacklist the acer-wmi kernel module:

sudo nano /etc/modprobe.d/blacklist.conf

add blacklist acer_wmi as a new line at the bottom of this file.

then reboot.

Or if you like one-line:

echo blacklist acer-wmi | sudo tee -a /etc/modprobe.d/blacklist-acer-wmi.conf