Rfkill

$ ifconfig wlan2 up
SIOCSIFFLAGS: Operation not possible due to RF-kill

list the rfkill restrictions:

$ rfkill list
0: hci0: Bluetooth
	Soft blocked: no
	Hard blocked: no
1: phy0: Wireless LAN
	Soft blocked: yes
	Hard blocked: no

Now unblock everything that's blocked:

$ rfkill unblock all

Now you should be able to bring your hardware up without issues:

$ ifconfig wlan2 up