The mystery of the "TI-30X Plus MultiView"-Hack

[Dyslexic-Referee]

I’m interested in the story around the "TI-30X Plus MultiView"-Hack. The TI-30X Plus MultiView is a downgraded version of the TI-30X Pro MultiView. Some features of the Pro, such as matrices and the numerical solver, were removed for the Plus to ensure that that Plus is within the regulations for schools in certain countries including Germany.

http://www.datamath.org/Sci/Modern/TI-30X-PLUS.htm states:

Quote:In July 2017 the Ministry of Education, Youth and Sport of Baden Wurttemberg informed all schools in the State that it is known since March 2017 to ''hack'' with a few keystrokes the TI-30X Plus MultiView and upgrade it to the original TI-30X Pro MultiView.

I also found this PDF online that appears to be the official document from the Ministry of Education, Youth and Sport of Baden Württemberg https://tiplanet.org/forum/download/file.php?id=4035
That letter states:

Quote:... dass es möglich ist, versteckte [...] Funktionen durch eine komplizierte Tastenfolge beim TI-30X Plus Multiview freizuschalten. Dazu gehören das im TI-30X Pro Multiview standardmäßig integriete Matrizenmenü (''matrix'') und das Menü zur Lösung von polynomialen Gleichungen (''poly-solv'').

Which translates to:

Quote:... it is possible to unlock hidden [...] functions through a complicated key sequence on the TI-30X Plus Multiview. These include the TI-30X Pro Multiview's standard built-in matrix menu (‘’matrix’’) and menu for solving polynomial equations (''poly-solv'').

So it really looks like there is a secret "code" that allows upgrading the software of a Plus to a Pro.
However nobody on the internet appears to know much about it even tough it has been years since the Plus MultiView has been replaced by a successor model. Does anyone here in the forum have any insights on it or maybe someone even knows the "code"?

(To avoid any confusion: This is about the MultiView variants of the calculators not about the later MathPrint versions which I assume where created specifically to address this issue)