It looks like Davee has maintained his word of a new downgrader even though the PSP's signing keys were released. The new downgrader will take your PSP running 6.31 or 6.35 firmware to the earlier 6.20 firmware, which is HEN-capable. The downgrade process is relatively simple: copy the PSP folder from the downgrader to your PSP and then put the 6.20 firmware update in the "PSP/GAME/UPDATE" folder with the file name "EBOOT.PBP".
How was this accomplished? Davee says the new downgrader uses the utility/power exploit to run the official PSP updater with a custom PRX running[...]
Continue reading: Davee Downgrades PSP FW 6.31 & 6.35 to 6.20...