As you knkow there is Yoshi's beta theoretacally it works( you know having two sticks one with cracked 2.0 and an originally 1.5 on the others, changing the sticks while black screen), all you have to do is change on memory stick 2 ´the update folder which is currently filled with version 1.5 of the firmware with 2.0 firmware now change memory sticks while you press three times power when it turns to black screen and then you can start update your psp 2.0 to a psp 2.0. i know that makes no sense. now if you press start the psp says you need no newer version.
Now the trick is to build a y-cable in which you can set in two memory sticks, the psp and you need a switch to switch thru the sticks,
because when you want to stick in another memory stick probably with 1.5 on it , the psp says upload progress cancelled because of pulling the stick out, with my theory it shouldnt recognize that you switched, then when you start it reads the hacked 1.5 in sfo is it 2.01, and voilá it should work. but im a coder not an electrician, need someone to do that.
Hope you understood me im German...
But thanks for reading.