want to point out that if you don't have a dongle, you can also use a PSP with CFW. You'll also need a blu-ray movie (just realized i don't even have 1!)
PSGroove.com - PS3Jig - PS3 Factory/Service Mode "Jig" Dongle for Sony PSP
if you don't have either, then you'll need to borrow one.
anyone have a link to the downgrade post?
UPDATE: I got this working. 40GB CECHG - CFW 3.55 To OFW 3.55 To CFW 3.41 To OFW 2.30, factory service mode, run files on USB (black screen), take out of service mode.
logic board remarried and games now loading. Not sure if all the steps is needed with my downgrade but it was my first time trying w the hardware that i have... but it worked. did not test blu ray yet, might test later as I use another system for movies anyway.