For those of our PAL friends that have a 1.50 Demo Unit PS3, good news for you! PS3HaX Member enclave123 has manually bruteforced his way through his PAL PS3 which was locked in demonstration mode, and successfully unlocked it.
Hold L1, R1, and select simultaneously when the security settings icon is selected in the XMB. Then it'll ask for you to input a code. In this case it's 8-6-0-4, This will unlock it from demonstration mode. (There is also the code 5-2-0-2 which is said to work on many NTSC Demo PS3's)
While this has only been tested on a PAL PS3, there have not been any tests on other region PS3's, try it out and let us know your results! Good job enclave132!