Is there any?

how to downgrade psp 6.37 ver fw to 5.5 m33-6 without pandora battery and how work psp tool in 6.37

Some Games require higher version of firmware. You need to make sure that the games you put on your stick is capable of running in 3.71 m33-2 else I would suggest upgrade it to the 5.x m33 version.

install some other firmware and then install m33 again

Sony has blocked access to homebrew since 1.51. The higher the version the harder to degrade.

The M33 installer is considered as homebrew.

You need to downgrade to 1.50 with a pandora's battery and a MagicMemoryStick.

Buy one at http://www.ebay.com/

The you will be able to use the M33 installer.

The "Data is Corrupted" is a hoax for sony to trick players into deleting the Very, oh so, Very UNcorrupted Application.

Someone will have to run the flash program to get you back to M33. Pandora battery and Magic stick with M33 flash on it. Most homebrew and programs will not run on any M33 version above 3.9. New UMD games from sony will have the latest firmware and the children will usually run the firmware upgrade to play the game. It will allow the new UMD to play, but the Sony Firmware will write over the Custom M33 firmware and you will not be able to run the games on your Memory stick.

google it type in psp hacks, or download 5.01 m33 iso or any torrents would do the trick

hi your previous psp version is 3.80 m33 if yes your using custom firmware that why you can play game to your memory stick the problem is you upgrade your psp firmware to sony official firmware 5.01 you reinstall your firwmware again using custom firmware like 5.00 m33-3 cfw below with m33 or OE

The reading of ISO games doesn't depend on your memStick...it really is about the firmware of your PSP, wether it is a Custom Firmware (meaning it has been modded/installed with a hacked firmware) or an Official Firmware by Sony...If your PSP firmware version has a M33 suffix, then it can play most ISO/CSO games...on the other hand, if your PSP DOES NOT have a M33 suffix, then it is an Official Firmware by SONY therefore, it CANNOT play ISO/CSO games and other homebrew apps...

You can update the PSP via the Network Update on the PSP, or by manually downloading the file onto a Memory Stick from http://www.us.playstation.com/PSP/About/SystemUpdate/pc.html

? You bought the firmware? Its supposed to be free. I think you got ripped off. It automatically updates if you connect the psp to a wi-fi network, and you can also update it by connecting the psp by usb to your computer.