Installing PSP custom firmware 4.01 M33 & 4.01 M33-2

Requirement : Firmware higher or equal 3.52 M33 and lower then 4.01 M33
Installing Custom Firmware 4.01 M33-2. This article assumes that you have custom M33 firmware M33 installed on your PSP and want to upgrade to
version 4.01 M33-2.

Section C – Install custom firmware 4.01 M33

Files to be downloaded and extracted:
Custom firmware 4.01 M33 and Official firmware update 4.01

Steps to install:
-Copy the folder UPDATE and its contents to your PSP’s memory sticks’s /PSP/GAME/ folder (eg. G:/PSP/GAME/).
-Rename Official firmware update 4.01 (EBOOT.PBP) to 401.PBP.
-Copy the file to your PSP’s memory stick’s /PSP/GAME/UPDATE folder (eg. G:/PSP/GAME/UPDATE/).
-Go to Recovery mode (Power off your PSP by holding the power button for 10 seconds. Turn on your PSP while holding the right shoulder button to go into recovery mode). Revert your kernel to 3.52 (or any kernel above 3.52 like 3.90). Exit the Recovery mode.
-In your PSP, browse to your Memory Stick and run the program 4.01 M33.
-Your PSP is now running custom firmware 4.01 M33. You can now delete the folder UPDATE folder from your PSP.

Update to custom firmware 4.01 M33-2

Files to be downloaded and extracted:
Custom firmware 4.01 M33-2

Steps to upgrade:
-Copy the folder UPDATE and its contents to your PSP’s memory sticks’s /PSP/GAME/ folder (eg. G:/PSP/GAME/).
-In your PSP, browse to your Memory Stick and run the program M33-2.
-Your PSP is now running custom firmware 4.01 M33-2. You can now delete the folder UPDATE folder from your PSP.