Bootscreen, Loadscreen.

[HybridNinja]

Yes I know, there's like probably a thousand of these threads, but I've looked through quite a few and most of them are for older firmwares, so to be safe, can anyone post links on how to change both the screen when turning your psp on, and how to change the screen when loading an app, or UMD. Sound changing would be good to. I am using 3.90 m33-2 right now. Thanks.

[MicroNut]

You should use CXMB (http://www.2alien.info/) when testing custom themes before flashing them to the NAND
In fact, you can just use it permanently without any problems.
CXMB (http://www.2alien.info/) is a plug that will allow you load custom "Loadscreens and Icons" without the risk of semi bricking your PSP.

Loadscreen
Most existing game gameboot.pmf files (http://www.google.com/search?q=gameboot.pmf) will work on 3.90M33
gameboot.pmf = video played before game is launched

Q: I want to debrand or remove the PSP Logo that is on top of all my gameboots?
A: hex edit the opening-plugin.rco (replace 0x3A14 with 55)
This is not a noob operation. Only try this if you really know what you are doing.
It will remove the PSP Logo that is superimposed on top of gameboots.
Works on 3.71M33 to 3.90M33 firmware. Works on most lower firmwares, some lower firmwares this does not work.

Bootscreen
opening_plugin.rco = Cold boot video. (http://www.google.com/search?q=opening_plugin+for+3.90M33)
You can make your own (http://customizepsp.co.uk/forums/showthread.php?t=1216)
Or download (http://www.google.com/search?q=opening_plugin++download) many pre-built opening_plugin.rco's

Just remember to use CXMB (http://www.2alien.info/)!
Dont flash to your NAND unless your 100% sure all the files are good and you have enough room to copy the files.
Often the Flash0 runs out of room and many people don't think to make back ups of their original files first.

[mike_jmg]

CXMB is great