“In the off chance that YOU brick YOUR PSP during the upgrade process, please do not complain here. I moderate all comments and yours just will not be added.
Sony has released a couple firmware versions since my last posting, but here is a tutorial for getting the OE version of 3.40 running on your PSP. I am going to structure this HOWTO a little bit as a test, if you like this structure, let me know.
*NOTE* You will need at least 75% battery charge. You may also want to have your PSP plugged into the wall just in case. You will also need a larger memory stick, the 32mb one doesn’t cut it. 1 gig sticks are uber-cheap now.
Step 1:
Download the 3.40 OE-A Firmware, uncompress it, then copy the uncompressed files as follows:
PSP 1.50 Firmware: You will place the uncompressed files in /PSP/GAME
PSP 3.XX OE Firmware: You will place the files in /PSP/GAME150
Step 2:
Goto the game menu and run the 3.40 OE-A Update Maker. This will take a couple of minutes to create the DXAR file.
Step 3:
You will need to access the USB menu on your PSP go into the oeupdmaker directory and copy the newly generated data.dxar file to the 340oeflasher directory.
Step 4:
Once again go back to the game menu and now run the 3.40 OE-A Firmware Install. You will need to agree by pressing X. This will check the integrity of the DXAR file before attempting to flash the firmware to prevent bricking. Once this is complete, press X to turn off your PSP. Turn your PSP back on, and you are now running 3.40 OE-A!
This is the easiest way to upgrade your PSP. I upgraded mine in under 10 minutes following these exact steps.”