hi all im having a few problems updating my firmware on my psp

curently im running psp 5.50 GEN-D (full) but would like to update to the psp pro firmware

im getting multiple problems with the install its either complaining that i am not on a pro firmware so i cant update or its saying im not on 6.35 which im not cause gen-d seems to of stopped making firmwares idk what the deal is there

but anyway any help you can provide would be awesome to speed the process up a bit my psp details are

model:psp1003
serial:FB1764237
its not one of those tao199 motherboards or what ever its called
current fw: 5.50 GEN-d (full)
method installed:pandora battery and magic memory stick

also ive been told the pro is the best one but if you know of a better firmware please advise