Hi everyone ..
First i wanna thank this amazing site and its members ..
cause without it i would never dream of my Ps3 jailbroken and runing CFW ..

i downgraded my ps3 from
4.40 ofw to 4.40 Rogero >Rogero Downgrader> Rebug 3.55 > Rebug Rex 4.30.2
thanks to @playerkp420 thread :
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then when i went to Rebug 4.30.2 i did just what @DEREKTROTTER says :
to change from CEX to DEX using Rebug toolbox in this thread :

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everything worked fine and i did it successfully ..
i changed to REX and then after all that (where the problem started) ..
i tried to connect to ProDG Target Manager (had full intent to RTE )
and connected the ps3 to Router to PC and it connected ..
and to be honest i kind made a stupid move which i probably shouldn't ..
while the MW3 disk and game is running on ps3 ..
on PC (ProDG Target Manager) i right clicked on the ps3 while connected and chose (Reset) ..
immediately i noticed ps3 went to black screen (which before it was on private lobby) ..
tried to restart with ps3 button and it did but with black screen ..
went to recovery mode and it works ..
restored whole system (step5) and work for the next reboot but when i reboot it again (blackscreen) and system won't work till i keep pressing power but and hear 1 beep ..

i did update to rogero 4.40 again > Rogero Downgrader > Rebug 3.55 > Rebug 4.30 Cex again..
and it seems to be a problem with Dex only cause when i go to Rebug toolbox and switch to Cex ps3 work perfectly but when i switch to Dex black screen on next reboot ..

could it be my Dex Dump file (corrupted) ? should i extraxt eid_root_key again and do the cex2dex steps ?
is there something wrong with hard desk ? am i stuck forever in cex ?

sorry for taking long but i thought it will make it clear to you what i'm facing ..
so can you help me please with this ?? im really in need to hear from pros ..