Brick Fat PSP while downgrading Slim?

I was downgrading a PSP Slim, I created the magic memory stick and pandora's battery and the fat PSP was working fine, I put the battery and memory card in the Slim and the Pandora Menu came up and I chose to upgrade to 3.71 M33 but after it was done and I switched on the Slim I could see the main theme and it just froze, I couldn't see the icons... Then I go back to my PSP Fat and I open it and the same thing happens there :confused: I have no idea why that happened, but after I called my friend and he helped me and unbricked them both.. But I'm just wondering why did the Fat PSP become bricked?:confused::confused::confused:

Which version of the pandoras battery are you using (esperanto).

Hmm I have no idea lol

First I mspformatted the memory stick then I opened Despertar Cementerio and created the msipl.bin, then I modified the battery using Battery Creator and then I downgraded. I think there was something else I did but can't remember right now..

Then the lesson here is: pay more attention to what you're doing when you're handeling expensive hardware and modifying settings. =D maybe?

yeah, but my friend helped me fix it after :D