If you want to update your juniper SRX/EX equipment the easiest way to do it is to copy the new software to a usb key and insert it in your firewall or switch.
You can create a snapshot of the current Junos and configuration using this cmd:
request system snapshot media usb
After you insert the USB key, you will see that the USB is automatically recognised. It is however not automatically mapped and you have to do it manually (first open the shell with: start shell):
mkdir /tmp/usb mount -t msdosfs /dev/da0s1 /tmp/usb
You can find the device number (in this case da0 as soon as you insert the USB drive or by going into the shell and executing: ls /dev).
After the USB is mounted, you can issue your command:
request system software add /tmp/usb/name_of_the_software no-validate no-copy
After the installation first you have to reboot the equipment:
request system reboot
And if everything goes to plan, you can also copy it to the alternate slice:
request system snapshot slice alternate