You shouldn't have downgraded mate, you should have upgraded to Rebug 4.30.2 by following this guide:
1- Make NOR/NAND dump (optional):
Install latest version of multiMAN, plug in a FAT32 formatted USB flash drive into the right USB port, go to mmOS->Select any file->Open in HEX viewer->[SELECT]->[START]->DUMP LV2(NO)->DUMP LV1(NO)->DUMP FLASH(YES)
2- Install Rebug 4.30.2 from XMB:
Download Rebug 4.30.2 from Rebug's website, rename the PUP to PS3UPDAT.PUP and put it on your FAT32 formatted flash drive in PS3\UPDATE and 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- Enable QA:
Install Rebug Toolbox from Package Manager, launch it and enable QA under Utilities. This is to ensure easier and safer downgrading.
4- Install Rebug Update Package 0.1:
Download Rebug_Update_Package.pkg from Rebug's website, install it from Package Manager, launch it under Games, follow the on screen prompts, PS3 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. You can also change System Mode to Rebug to spoof to 4.40, XMB Operation Mode to Retail and Debug Menu Type to CEX QA. This is to ensure you have the Retail menus instead of the Debug menus which you probably don't need.
CECHL 500GB: OFW 2.50 > OFW 2.76 > OFW 3.41 w/ dongle > OFW 3.55 > 3.55 kmeaw > Rebug 4.30.1 > Rebug 4.30.2
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