This article will help you downgrade you r PSP from v2.0 to v 1.5.
I can say from first hand knowledge that this method has been known to be perfectly safe and work well if you follow the directions. Downgrading from 2.0 to 1.5 The following three files are necessary...
MPH Downgrader
1.50 Update EBOOT
2.0 Update EBOOT
You will need to upgrade to 2.0 first, if you're using 1.51 or 1.52. Also note that many antivirus scanners will incorrectly detect the downgrader as a virus. You can see here it is 100% safe to use.
Remember this will ONLY WORK on a PSP with firmware V2.0.
* You need to unzip the files MPHDowngrader.zip and EBOOT_1.50.zip. Use a program such as WinRAR, 7Zip, or WinZip (check Google). Once they are unzipped, you're ready to start the process.
* Connect your PSP to your computer via the USB cable.
* Once the connection is set up, open up My Computer and browse to the removable disk that is your PSP. There will be a few things we will have to setup here.
* Go ahead and double click on that to open up your PSP on your computer, you'll be in what's called the root menu. There will be a PSP folder showing if you are in the right place.
* Copy the following files over to this root directory. Make sure it is in THIS location IN the ROOT folder...NOT in the PSP folder or any other folder. Index.dat and h.bin should both be put into your root directory.
* Once this is done, open up the PSP folder and then open up the Photo folder. Here, you will copy over overflow.tif file, but make sure you keep it in the Photo directory and not a sub directory.
* Now, go back to the PSP directory and this time go into the Game directory. If there is not one already there, create a folder called UPDATE. It MUST be called UPDATE and nothing else.
* Open up the new UPDATE folder you just made and then copy EBOOT.PBP into this folder from your computer. Once all of this is done, you're ready to start downgrading. So far, so good.
This is vital! Double check that you followed the above instructions to the letter before continuing.
Good now you can continue.
* Disconnect the USB connection from the computer and plug the AC adapter into your PSP. As with all upgrades, you must have a certain percentage of battery life as well as the AC adapter plugged in, or this will not work properly.
* Now go to the Photo icon on your PSP and scroll
through the pictures to get to overflow.tif. You do NOT have to press anything. It will start automatically. Two strings of letters/numbers will appear. This is normal and good.
* Wait AT LEAST 30 SECONDS and then turn off your PSP by holding the power button up until it fully shuts down. Then, go ahead and start your PSP up again.
* Now you will now have to go over to the Game icon and scroll down to memory stick. Select this and you should see the 1.5 update.
* Go and select it and start it up. Go through it as you've done before with your 2.0 update and follow the prompts. When the update reaches 99% it will crash and show an error. THIS IS OKAY. DO NOT PANIC. Once again press the power switch up until it fully turns off.
* Now, turn the PSP back on. You will get another error. Just press the "O" button and it will restart after rebuilding the system data. Then just set it up as you did when you first got your PSP and you have a brand new 1.5 PSP. Be responsible with it and don’t abuse it.
