I'm trying to repair a PSP 4 my friend, and it looks like its cheaper to replace to main circuit board. so i'm just wondering what version is easiest to mod.
Repairing a brick, eh? Well as long as your FW version is less than 3.03-you're in luck-you can downgrade and mod to your hearts content (or your friends' rather)
All you need is a v1.5 PSP. Then, go to Dark_Alex's site and download one of the firmware's I reccommended. As far as the v1.5 psp board you found, I have no idea how you'd go about installing it.
It's the main circuit board, so couldn't I just replace the current board? i need to replace the board anyway cuz BIOS won't boot, the back light comes on, but that's it.
provided that the board from eBay is indeed version 1.50, you can just swap it out and then use one of the custom firmwares from Dark_Alex to upgrade to 3.40OE-A