Here is the step by step procedure for 1140 series AP.. Its the same for almost 90% or all the Aironet product series
Assuming We have the IP 192.168.100.101 assigned to the LAPTOP or the DESKTOP Ethernet port which runs as the TFTP server and assigning 192.168.100.100 as the IP to AP.
Make sure you have the TFTP server or download it from google (tftpd32.exe)
Using the CLI
Follow the steps below to reload the access point image using the CLI. When the access point begins to boot, you interrupt the boot process and use boot loader commands to load an image from a TFTP server to replace the image in the access point.
First of all, I would like to let you know that there is a problem if you don’t see the extensions of the files in your folders. The problem is that, when you rename the file, you just rename the name, and not the extension.
The solution for this is:
Go to the folder that contains the IOS image and go to the tools option in the window bar. Click on folder options Go to the view tab and uncheck the option that says: “Hide file extensions for known file types”.
Note Your access point configuration is not changed when using the CLI to reload the image file.
Step 1 Open the CLI using a Telnet session or a connection to the access point console port.
Step 2 Reboot the access point by removing power and reapplying power.
Step 3 Let the access point boot until it begins to inflate the image. When you see these lines on the CLI, press Esc:
If you do not press the spacebar to continue, the process eventually times out and the access point stops inflating the image.
Step 8 Enter the set BOOT command to designate the new image as the image that the access point uses when it reboots. The access point creates a directory for the image that has the same name as the image, and you must include the directory in the command. Your entry might look like this example:
ap: set BOOT flash:/c1140-k9w7-tar.124-21a.JY.tar
ap: set BOOT flash:/c1140-k9w7-tar.124-21a.JY
Step 9 Enter the set command to check your bootloader entries.
Step 10 Enter the boot command to reboot the access point. When the access point reboots, it loads the new image.
This will get the AP to Autonomous image AP# prompt after reload..