Just install Rebug 4.41.2 on top of 3.55 by following the guide below:
1- Install Rebug 4.41.2 from XMB:
Download Rebug 4.41.2 from Rebug's website, verify the md5 hash, rename the PUP to PS3UPDAT.PUP, put it on your FAT32 formatted flash drive in PS3\UPDATE, go to System Update and Update via Storage Media. Make sure there's NO original game disk in the drive and that you DON'T Update via Internet or else you would risk installing OFW higher than 3.55!
2- Enable QA:
Install Rebug Toolbox from Package Manager, launch it under Games, go to Utilities and enable QA. This is to ensure easier and safer downgrading.