itskamel's Dummy_BDEMU tutorial for REBUG REX
This is for people who have a broken blu ray drive but their logic board is still working and are having issues playing some backups. This is only available for use on REBUG REX firmwares 3.55.3 and 4.21.
Requirements
1. Pc and a PS3
2. USB stick (512MB minimum)
3. Disc Image Generator Software (ps3gen)
4. Playstation3.iso Dummy BDEMU image
5. REBUG (REX) CFW 4.21 or REBUG (REX) 3.55.3 operating in DEX mode with DEX lv2_kernel (FULL DEX MODE)
Step 1.
Step 2.
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Connect a USB HDD to your PC to be used for BDEMU
Step 3.
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On your PC run ps3gen and RUN AS ADMINISTRATOR, then click the "show" button in the top right hand corner. Next click "Select File", then locate the "PLAYSTATION3.iso" that you extracted to your desktop earlier. Next click "Save / Emu" button". Then select "Write image to BD EMULATOR HDD". After that you will select your BDEMU HDD, lastly you will pick a slot from the list and click "Write Image".
Step 4.
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Now moving on to the REBUG firmware, you will need to install the "REBUG TOOLBOX" (this was also in the rar file that you extracted to your desktop.
install it by putting it on the root of a usb stick and via install pkg files "standard location".
Step 5.
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Setting up REBUG TOOLBOX to use with Dummy_BDEMU
Open "REBUG TOOLBOX" and choose the following settings.
"SELECTOR"
REBUG MODE / DEBUG XMB / DEBUG MENU
"DEX / CEX"
The following nor/nand for dex is needed from any cfw 3.55
Flash your DEX EID0 NOR/NAND file (DEX-FLASH.EID0.NORBIN or DEX-FLASH.EID0.NANDBIN file on /dev_usb000 stick)
Now hold down circle to quit the toolbox and restart the PS3
Step 6.
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Go to debug settings in the xmb and choose the following.
Blu-Ray Disc Access to BD Emulator (USB)
Next turn off the ps3.
Step 7.
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Connect the BDEMU HDD drive/ stick to the far right port on the ps3 (the one closest to the blu ray player), and then turn on your PS3.
Now you should see "PLAYSTATION3" Game Disc mounted in the XMB game column.
Step 8.
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Install multiman 4.10.00 via pkg manager (this again was one of the files you extracted earlier).
Step 9.
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Start up multiman 4.10.00 from the xmb and then load a game from your internal or external HDD (connected to another port)
DO NOT UNPLUG THE BDEMU USB DRIVE!
Step 10.
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Start your game from the Disc Icon in the XMB
Step 11.
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Use the like button if this helped. 3rd tut in 3 days. phew.
andbey0nd as you requested, hopefully this will help some people. Although it is almost everything you said word for word in your release notes. 
credit to
@
Marsha223
for the fix.
(although I thought everyone already knew you had to run as admin when the ps3gen 3.6 backup method was released) >.<
enjoy - kamel