Yes, you have read the title right - 2.50/2.60 Downgrader. Dark_Alex, along with Mathieulh and Yoshihiro from SonyXTeam, have released the first working 2.50/2.60 downgrader. If you updated you PSP to v2.50 or 2.60 read this little tutorial to downgrade it to v1.50.
ONLY use this if your ORIGINAL FIRMWARE was 1.50, 1.51, 1.52, 2.00, or 2.01 from the FACTORY and you updated to 2.50 or 2.60. If your ORIGINAL FIRMWARE was/is 2.50 or 2.60 then do NOT attempt to use this DownGrader version!
This software is free , and I'm not responsable if it causes damages to your PSP. If you use this software, you agree that you are using this program at your own risk and that you won't blame the author for that. The needed tools are here.
1. Download the attached files.Unrar them and copy the folder inside folder 2.50 if you have a v2.50 PSP
2. or the folder inside folder 2.60 if you have v2.60 PSP.If you asked, press yes to replace the folders.
3. Copy the folder DOWNDATER to the root of your memstick.
4. Init GTA and the eLoader
5. In the eLoader menu, choose the downdater test. WARNING: the program won't output any display and any warnings, it will init the downgrader process inmediatelly.
6. You'll see that your memstick flashing. That means that your psp is being flashed from the memstick.
7. You won't see any type of output in the screen (this is for safety). When the memstick finishes of flashing,
WAIT at least a minute, and then reinit your psp by holding the power button.
8. That's all. If all went right, you'll have 1.50. If it went less good, you'll still have 2.50/2.60. If all went wrong, you'll have a bricked psp(except in the case you have the modchip). Remember that you have accepted that risk.
9. If your PSP is showing up as v2.01, this is fine. Just use Wab Version Changer and change it to v1.50.
Note1: For those of you wondering why your UMDs say "Disc cannot be read," take your battery out of your PSP (for up to 5 minutes) and then put it back in your PSP. Your UMDs will then work!
Note2:As a note i have a jap psp & used the north american 1.5 update package but everything went fine & no problems were reported.