[sexybeast099]

Okay, to everyone (simonc and xxmynameisjohnxx especially) you need to use pandora's battery to get your psp into a custom firmware if it's new. If you buy used, it has to be below OFW 3.51 to downgrade without pandora and even then it's really complicated. Anyone who wants to downgrade to a lower firmware version needs pandora's battery. The risk depends on if you do a method to open your battery or if it's using a special tool (Datel Battery Service Tool, separate CFW PSP). If you open your battery like the guide in my signature suggests, it could potentially be dangerous to your health and/or the functionality of the PSP. Read the guide for more information and post in that thread for any more questions about pandora's battery.

@pate: You need to explain more about your situation. what were you doing at the time exactly? What firmware are you running? Are you following any guides (*hint, hint* look at the one in my signature)? Be sure to tell us what's going on in more detail and we could possibly be of assistance.

@allain2006: Are you asking for a 4.05 M33 Firmware from Dark AleX or are you asking if there's a way to put a custom firmware on a 4.05 OFW PSP? If it's the former, Dark AleX doesn't really take requests like that as would be evident if you visit his site. If it's the latter, please read the numerous posts by me (among others) stating that you can if you use pandora's battery.

A warning to all those who ask how to downgrade or otherwise turn their psp's into custom firmware running systems: you will not be answered anymore by me. you should read the threads more than just glancing at the first page and, on top of that, should SEARCH the forums for your question before posting.