1. Managed Mode (Automatic Update)
If a SonicPoint device exchanges Sonic Discovery Protocol (SDP) & SonicWall Simple Provisioning Protocol (SSPP) with a SonicOS appliance, it will enter the managed mode. Under this mode, SonicPoint firmware can be automatic updated.
Step 1: Connect one LAN port on the SonicPoint to a SonicOS appliance interface.
Step 2: Login to SonicOS firmware | Navigate to the Network | Interfaces page | click Configure for the interface to which your SonicPoint is connected.
Step 3: Configure the interface as following. Here using the standard wireless zone WLAN for the Zone type.
Step 4: Navigate to SonicPoint | SonicPoints, the connected SonicPoint device will be displayed in SonicPoint area.

no Internet connected but there is one managed SonicPoint in the same network with an appropriate updated firmware , this SonicPoint can also grab the firmware automatically . (The SonicPoint with updated firmware can be the seed SonicPoint. SonicOS will firstly check its managed SonicPoints and if there is no appropriate firmware, SoncicOS will try to get the firmware from the Internet.) 
2.Managed Mode (Manual Update)
Step 2: Load the SonicPoint image onto a local Web server that is reachable by your SonicWall appliance.
Step 4: In the text box, type the URL for the SonicPoint image file on your local Web server.
Step 4: Go to System | Firmware | Click HTTP-Select and Upload New Firmware | A window will popup.
Step 5: Click Choose File | Select the prepared SonicPoint firmware | Click Upload button. The SonicPoint will be upgraded.