@Zone x sad to say but 9 times ten times its the users fault, either they download the wrong reverter to the firmware they have installed, not changed the file name or even using the wrong type of usb stick.
If anyone who still owns a PlayStation 3 tries either THIS PS3 4.86 Demo Reverter via @zelis82 or THIS PS3 4.86 Demo Reverter via @moonone let us know which you tried and the results so we can update the OP accordingly thanks.
PS3UPDAT4.68Reventor.PUP via @zelis82 work for me. I was have console with 4.85 Demonstration mode. Helped only update to his version. Sorry for my english.