PS3 Switching from Rebug 4.82 LITE to 4.81 REX Problem

Hey guys.
This isn't actually my problem, rather of a friend.
So, he bought a PS3 to jailbreak it. He doesn't downgraded it by himselfe. He went to a Modshop to jailbreak his console. But now the problem is, he is on Rebug 4.82 CEX and wants to change to DEX. But this isn't possible on Rebug 4.82 LITE.
When I tried to downgrade it to 4.81 REX, it doesn't work. I don't know why. In the Recovery options it says minimum 4.82. But I also downgraded my one from 4.82 to 4.81 without any problems.
On my one it said, minimum 2.50. (I Softbricked my console, thats why I did it in recovery mode)
We also tried it from the XMB, doesn't work either. No he is stuck on 4.82 and can't use Mod Menus, Webman, copy all files to a bigger hard drive with the debug settings and so on. (He tried a GTA 5 sprx mod menu, it loads up, shows the welcome message but he can't open it)

One thing we didn't tried is using Ferrox 4.82. But I don't have any experiences with Ferrox.

He got a PS3 Slim CECH-2504A Console.

 

maybe he's not qa flagged?

 

That could be possible. We will try ^^

 

i had the same problem when i first exploited my ps3 on 4.82 i can help
in your usb make shure you you this path PS3/UPDATE/PS3UPDAT do not rename the updat file to PS3/UPDATE/PS3UPDAT.PUP or it will not read it when you try to look for it in the update column on the xmb menu..good luck!

 

also i believe rebug 4.82 lite comes with QA toggle already enabled .this allows you to swap custom firmware with no problem just install rebug toolbox in your package files and open it and verify your QA toggle option is enabled

 

So, just use the standard Rebug update file name?

 

the name of your update file inside the UPDATE folder should say PS3UPDAT exactly if not rename it like so exactly. see i was on 4.82 lite rebug and when i tried to install 4.81 it would say no applicable data found .and when doing it through recovery mode it would say please install 4.82 or higher and as soon as i named my update file PS3UPDAT NOT PS3UPDAT.PUP... it worked.