at first my PSP version was 3.52 M33 then i update it to 3.71 M-33 then i update it to ofiicial firmware 3.80. why is this possible from custom firmware to official firmware? & can i change it to 3.80M33 . also it may be noted that when my firmware is 3.52 M33 i cant upgrade it to official firmware 3.70 so why is this possible to upgrade it to 3.71 M33 to 3.80 plz answer the question