Here's a guide to install Rebug 4.30.2, but first, you have to pass through a 3.55 CFW to extract your eEID Root Key to be able to convert to DEX later. You can only exract your eEID Root Key on 3.55 CFW. Once you extract your eEID Root Key, install Rebug 4.30.2 by following the steps below:
1- Make NOR/NAND dump (optional):
Install latest version of multiMAN, plug in a FAT32 formatted USB flash drive into the right USB port, launch multiMAN under Games and go to mmOS > Press [O] on any file > Open in HEX viewer > Press [SELECT] > Press [START] > Export GameOS LV2: Select No > Export HV LV1: Select No > Export FLASH: Select Yes
2- Install Rebug 4.30.2 from XMB:
Download Rebug 4.30.2 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!
3- Install Rebug Update Package 0.2:
Download Rebug_Update_Package_0.2_4.30.x.pkg from Rebug's website, verify the md5 hash, install it from Package Manager, launch it under Games and follow the on screen prompts, the screen will freeze for a while when you select Yes, do NOT force shut down your PS3 at this stage or else you will get a nice and shiny RSOD! Just be patient and wait for it to finish what it's doing, it will reboot if needed when finished. Once the PS3 has rebooted, you can delete Rebug Update Package from your XMB as it is not needed anymore.
4- Enable QA and spoof to 4.41:
Go to Package Manager > Install Package Files > PS3 Hard Disk and install Rebug Toolbox. Launch it under Games, go to Utilities and enable QA. This is to ensure easier and safer downgrading. Now go to Selector and change System Mode to Rebug, this will spoof to 4.41 to prevent accidental updates and allow PSN access (with abn risk).