I think saying the end of Enlightenment was totalitarianism is a bit too negative, thus I will offer a more positive reading.
Wir hegen keinen Zweifel (…), dass die Freiheit in der Gesellschaft vom aufklärenden Denken unabtrennbar ist. Jedoch glauben wir, (…) dass der Begriff eben dieses Denkens, nicht weniger als die konkreten historischen Formen, die Institutionen der Gesellschaft, in die es verflochten ist, schon den Keim zu jenem Rückschritt enthalten, der heute überall sich ereignet. (…) (S)chon der Mythos ist Aufklärung, und: Aufklärung schlägt in Mythologie zurück.
We do not entertain any doubt [...] that the freedom within a society is inseparable from enlightenment thought. However, we think [...] that the concept of this very kind of thought, no less than the particular historical forms it took, the social institutions it is woven into, does already contain the seed of all the regression we witness everywhere these days. [...] The Myth already is Enlightenment, and into mythology the Enlightenment falls back.
In other words: The progressive nature of Enlightenment, the freedom of thought and the fluidity of institutional status that is at its core, are in constant dialectical opposition with the institutional stability that enabled the very possibility of Enlightenment and into which it leads as soon as the progressive ideas become institutionalised.
If we want to take Enlightenment positively, we must concentrate on the progressive (not for the sake of progress itself, but freedom), processual gist of Enlightenment instead of institutionalising its goal of "getting hold of" nature and ultimately man (and their fears) themselves in the form of calcinated institutions and structures of power. Therefore, we have to constantly and actively keep ourselves in a dialectical process that questions institutional structures and breaks them up as soon as they hinder freedom and progress.
Enlightenment in this sense, according to Adorno and Horckheimer, is by definition a continuous dialectical process that never ends. What we need in order to have the idea of Enlightenment coming to itself (to use Hegelian terminology) is what the SEP article calls dialectical Enlightenment of Enlightenment, the constant self-empowerment of thought and freedom.