Firmware 3.03 to 1.50 question

Is the only way to downgrade from 3.03 is to have GTA LBC or Pandora's battery?

If there is another way, can someone point me in that direction? Thanks!

If you have a copy of lumines, you can update to 3.50 and downgrade using the exploit from that. Other than that you've already listed your only other 2 options.

Can I upgrade to 3.03oe-c with the current firmware 3.03? or any other custom firmware I can put on the psp?

I think yes but i recommend to downgrade first...and after upgrade understand..by Downgrading you have more chances to go to the custom firmware..[NOTE: why dont you get a pandoras Battery and Downgrade?] If you have a friend with custom firmware also works...

No it wont work, you can knock yourself out and give it a shot but the program wont run.