PS3 CFW 3.55 kmeaw upgrade to Rebug scare experience! brick?!

I thought my PS3 game console was bricked after PS3UPDAT.PUP from 3.55 kmeaw to REBUG 4.30.2 REX. The brick symptom is when pressed power button, it will power on for 5 second then turn off right away.
Q: Tried out recovery mode method, but unable to get to the mode! Panic panic panic, brick?
A: No, it is able to get into recovery mode after swapped HDD from 320GB to 500GB. (Good news!!!)
Luckily, I did backup by using PS3 backup utility before doing software upgrade.
   Make sure you have the REBUG 4.30.2's PS3UPDAT.PUP on FAT32 thumbdrive root \PS3\UPDATE\ folder for the PS3 System Update/Recovery/HDD upgrade procedure.
   The PS3 restore is working on REBUG latest version 4.81.2, but trophy since I didn't sync it.
My PS3UPDAT.PUP upgrade route: 3.55 kmeaw > REBUG 4.30.2 REX > REBUG 4.46.1 REX >  REBUG 4.78.2 REX >  REBUG 4.81.2 REX.
(Not sure if you can upgrade it from 4.30.2 to last version(4.81.2) right away?)

Note:
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FTP by using REBUG ToolBox is better than using it from Multiman.
Please use AOMei partition tool to convert FAT32 to NTFS for the backup HDD since file sized over 4GB won't able to save on FAT32. Just FYI.