How to Run Downloaded Games on a PSP (with Pictures) - wikiHow
PlayStation Portable (PSP) 6.61 firmware download
How to Mod Any PSP on Firmware 6.61 or Lower! - Infinity 2.0 Permanent CFW - YouTube
PSP: First hacks for the new Firmware 6.61 - PRO CFW & Downgrader updated! - Wololo.net
Release: Infinity 2.0 – Enables Permanent 6.6x Custom Firmware for all PSPs! - Wololo.net
How to Download PSP Games and Transfer them to Your PSP
PSP 6.61 Firmware Update Download
I tried installing 6.61 PRO C2 and infinity v2.0.3 on my psp 3001 (following the instructions on the CFW guide of this subreddit) but it just shows corrupted data when I disconnect,