The PS3 cannot read USB drives formatted to NTFS or exFAT.
Some work, some don’t. You must check the "Date Code."
Do you know the or date code of your PS3 to confirm if it supports this process? how to downgrade ps3 firmware 4.89 to 4.88
Since you are on 4.89, you cannot simply install a 4.88 update file over it; the PS3 will block it as an "older version." You must exploit the system memory (Flash) to allow the installation of older or custom software.
If your goal was to get back to a "clean" 4.88 Official Firmware (OFW): Install the 4.88 CFW first using the steps above. Once on CFW, the system restrictions are gone. The PS3 cannot read USB drives formatted to NTFS or exFAT
Since the official BGToolz site often fluctuates, find a reliable 4.89-compatible mirror.
Before attempting a downgrade, you need to know the "Base Firmware" your console shipped with. If your base firmware is 4.89 or 4.90, you cannot go back to 4.88. Download the tool. Since you are on 4
Place the PS3UPDAT.PUP file on a FAT32 formatted USB drive in the folder path: USB -> PS3 -> UPDATE .