Do Beings go into total unconsciousness before attaining Buddhahood? I am asking the Vajrayana/Mahayana view as I already know the theravada view.I heard that Buddhas only have jnana and not vijnana wich means they are inert like rocks but 'act' based on past merit and deeds ,


there is a sutra passage cited in the Yogācārabhūmi viniścayasaṃgrahanī that states:

&quot;Bhagavān, how should the mental factors of the tathāgatas be known?&quot;
&quot;Mañjuśrī, the mind (citta, sems), intellect (yid, manas) or
consciousness (vijñāna, rnam shes) of tathāgatas are indeed not
differentiated in discerning wisdom, but the mind of a tathāgata
arises without formations, and should known to be like an emanation.&quot;
&quot;Bhagavān, it being the case the dharmakāya of the tathāgatas is free
from all action of formations, on the other hand, do mental factors
arise without the action of formations?&quot;
&quot;Mañjuśrī, it is due to past cultivation of method and wisdom.
Mañjuśrī, one awakens [from sleep] because of the power of past
formations, but though there are no formations for arising in the
concentration on cessation, one arises [from concentration] only
through the power of past formations. Just as like the mental factors
of sleep and the concentration on cessation, the mental factors of the
tathāgatas should be known to be formations of past cultivation of
method and wisdom.&quot;
&quot;Bhagavān, do the emanations of the tathāgatas have minds or not?&quot;
&quot;Mañjuśrī, Though they do not have minds, they are also not mindless,
because minds are neither independent nor dependent.&quot;

so they're like robots.How true is this?and if it is true,isn't suffering but existing for all intents and purposes better than not existing and not suffering?.
There's a nice paper on the topic, called &quot;Why the Buddha Never Uttered a Word&quot; by Mario D’Amato - you can find it on Academia website.
You'd do best to read it all, although you may certainly prefer to skip to a section titled &quot;Mindful Buddha versus Mindless Buddha&quot;.
There Mario cites some other work that says:

... Dunne goes on to specify that according to Candrakīrti’s account of buddhahood, for buddhas “the fluctuations of mind and mental functions” have “completely ceased”. Jayānanda (c. 1100), the only known Indian commentator on any of Candrakīrti’s works, affirms Candrakīrti’s account and “explains that enlightenment is a process of ‘not knowing’ and is characterized by the elimination of the knowing instrument, the mind”.
…
Dunne states that, according to Candrakīrti, “the dharmakāya causes a didactic sound to emit from a buddha... [but] the production of this sound does not at all mean that a buddha is cognitively active”. Being mindless, a buddha is unable to use language in any ordinary sense; on this view, a buddha only appears to use language—what is actually occurring is that certain sounds emanating from a buddha are interpreted by unenlightened beings as words and language.

Mario then goes on to argue that, in his understanding,

... it is only metaphorically the case that buddhas do not use language. On the model of the awarenesses of a buddha considered here, a buddha possesses both a nonconceptual and a conceptual awareness, and it is a buddha’s possession of some form of conceptual awareness that allows for the use of words and language. However, through the attainment of nonconceptual awareness—through directly apprehending
thusness, the fundamental, ineffable nature of things—a buddha’s relation to conceptualization and language has been radically altered. In any occurrence of language use, a buddha would remain aware that putative linguistic referents do not actually exist. A buddha would employ language without falling
under the spell of words and objects—employing concepts and language in perfect accordance with conventional usage, while remaining aware that ultimately there are no referential objects. We might describe a buddha’s mindful awareness in terms of what some contemporary philosophers have referred to as fictionalism.
Stanley states: “On a fictionalist view, engaging in discourse
that involves apparent reference to a realm of problematic entities is best viewed as engaging in a pretense. Although in reality, the problematic entities do not exist, according to the pretense we engage in when using the discourse, they do exist”. According to such a fictionalist view, one might engage in conventional discourse without positing that the entities referred to in such discourse ultimately exist, for example, through adding an operator “in fiction F” (or “according to the conventional domain”) to any truth claim. Hence, on a mindful buddha account, a buddha may be said to use language “under erasure,” employing words while remaining mindful that words do not actually refer in the way they purport to—mindfully aware that referents are nothing more than fictions.

I, for one, agree and approve of this explanation.