kk so you will need:
-USB Stick
-Computer
-PS3 of course

Tutorial:
-KK download the UPDATE.PUP here
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-After you download it make a folder in your USB stick called PS3. Inside make another folder and name it UPDATE. The letter have to be capitals.
-Now drag the folder and put it in the UPDATE folder.
-Remove the USB stick from you PC and plug it in your PS3
-Go to system update and select the option that says "update via storage media" or something like that. It should find the official firmware and press "ok" and wait until it goes back to the official firmware.
Hope i helped!

(I dont realy care about the maps)