[TUTORIAL] How to install debug firmware on retail PS3 (partially-HDD swap method)

Note: For this to work your system must be below or at 1.80 for the 1.80 debug update and below or on 2.01 for the 2.15 debug update. Just use the next version up from your current firmware version for the retail update.

How to install debug firmware on retail PS3:
Tools needed:

• 1 PS3 system
• 2 PS3 hard drives that are the same size
• 1 retail firmware upgrade (DOWNLOAD HERE)
• 1.80 Or 2.15 debug firmware (DOWNLOAD HERE)

Instructions:

1. Format both hard drives on the PS3 system.
2. Download a debug PS3 firmware and place it in USB stick, and start the update. This will copy all the debug firmware files to the PS3's HDD-A.
3. After copied the PS3 will restart and you will see the normal update menu which prompts you to click the button to start update. Do NOT update your PS3, but power it off.
4. Next remove the HDD-A, and place in the second HDD, HDD-B in the PS3.
5. Download and copy a retail PS3 firmware to a USB stick.
6. Again as before place USB in PS3 and update the PS3 as normal but when you get to the screen where it asks for you to press button, do that but stop when it asks you to AGREE to Terms and Condition Page.
7. While the system is still powered on and on the update screen, REMOVE HDD-B, and insert HDD-A.
8. After swapping the HDD's continuie to update the PS3 as normal and the PS3 will install the debug PS3 firmware!
9. Go to the settings and check firmware version and there you will also see the debugging PS3 options

UPDATE 1:
For those who are seeking to do this method with 2 diffrent hard drive sizes, a method has been found: