Help with downgrading

I haven't veen using my PSP much... for a long time. It hasn't even been upgraded for a long long time (a good thing... I think) it's version 2.6 right now and I want to downgrade it to 1.5... which I can't manage to do without the version 1.5 dump files and GTA, and tiffdowndater doesn't work for me since the psp just turns black when I try using eLoader and stays that way until I close the computer

Is v2.6 a good version to downgrade? and also I just want to play homebrew and be able to run iR Shell, any other way other than v1.5 ^^ thanks... and also a way that I don't have to go try and find a original or specified copy of a certain game...

two options,

1) get lumines (i don't think theres more then one version, and it is sold in stores) upgrade to 3.50 EXACTLY no higher or lower, then use the lumines exploit to downgrade (look it up)

2) find somebody with a hacked psp and have them make a padora battery for you, or hard mod your own and downgrade with that method

i'm not good with guides, so just look these up

I can make a Pandora Battery myself since I have the old version of the battery... I got 2 actually but anyway... what does a pandora battery have to do with downgrading... it's only for un-bricking... and you also need specific version of lumines. And how to you upgrade to a CERTAIN version like I want to upgrade to 2.71 but not go flying up to version 3.5