To downgrade (and get a custom firmware) or unbrick your PSP, you need the Pandora's Battery. There is three ways to get the Pandora Battery. You will also need to make the Magic Memory Card.
1. Find a someone who has a Custom Firmware that is willing to let you borrow their psp. You will use their psp to softmod the battery. Meaning using software to make the Pandora. If you willing to do this, follow this guide:
GUIDE
2. Hardmod the battery. Meaning that you have to open that battery up, and pulling out a pin. Note that if you pull the wrong one, your battery would be messed. If you are willing to do this, follow this guide
GUIDE
3. The most safest way, is to buy a premade pandora battery from the internet (use google or ebay).If so, follow this guide or use the same guide on the second step. I recommend buying from DealExtreme for $10.
GUIDE
NOTE : TA-088 motherboards - Sony has just made new motherboards that stops the usuage of Pandora. This does not count if you update your firmware
TA-088 v1 - Came with 3.71 firmware or higher. It can not make pandora battery, you have to get it somewhere else. It
still can get custom firmware.
TA-088 v2 - Came with 3.90 firmware or higher. Same as v1, but the magic memory card needs to installed with DC 7 ( It needs a custom firmware PSP) GUIDE TA-088 v3 - Came with 4.01 firmware or higher. Pandora Proof.
besides me buying the games and riping them on my own, is it 100%necessary to buy the pandora battery? if it is im wondring why... anyone has an explanation about it?
easy; the slim can only get custom firmware with pandora's battery and magic memory stick. the lowest it can go is 3.60, and there are no exploits eversince 3.50.
besides, it's the safest way to get custom firmware.