Firmware Installation Plan:

If you are installing an upgrade to a new release (ex 320_xxx to 340 or 350_xxx)
1) Power off the Managed System
2) Using the HMC GUI interface, click on "Updates" in the navigation (left-hand) pane. Click in the checkbox beside the Managed System.
a) Click on "Change Licensed Internal Code to a new release". 
b) After clicking "OK" on the readiness check panel, select the repository where the firmware files 
can be found and click "OK". Select the new firmware level from 
the selection panel displayed and click "OK".
c) Accept the license agreement and click on "OK" in the confirmation panels to start the upgrade.  

f) When the upgrade completes, both the Activate and Accepted levels will reflect the level just installed. To effect a complete overwrite of both sides of the Service Processor, you must continue with this procedure.
g) Click on " Change Licensed Internal Code for the current release".
h) Select "Advanced Features" and click "OK".

i) Select "Install and Activate" and click "OK".
j) After clicking "OK" on the readiness check panel, select the repository where the firmware files can be found and click "OK".
k) Select "Specific Levels" and click "OK".

l) Select the managed system, then select "Change Levels".
m) Select the same level chosen in step b and click  "OK" and then click "OK" again. 
n) On the "Select Installation Type" panel, ensure that the "Disruptive install and activate" radio button is selected and click "OK".

o) Accept the license agreement when it is displayed, and then click "OK " twice to confirm the action.
p) When the process completes, the Managed System may be powered on.

Business and Technical Assessment: 
Currently Our TL level is at 4 and customer wants us to upgrade it to TL6, but before upgrading our TL We checked with IBM Support and they advised us that our Firmware Level is below the prescribed level,hence we need to first upgrade our Firmware to the prescribed level and then proceed further.