I don’t quite understand why you equate beginninglessness with unconditionality. If samsara has no discernible beginning than the existence of every link in the paticca samuppada is beginningless. There has always been death, there has always been namarupa, there has always been ayatanas, etc.
Now, all of these links are obviously conditioned because they are included in the paticca samuppada process. So, as abstractions they are beginningless and conditioned. Therefore, it is not logically necessary for a beginningless something to be unconditioned. There may always be a condition for it, and this condition may too be beginningless.
If you ask specifically for the root cause of ignorance (as I don’t quite see what you mean with ‘energy’, it is too vague a word in that particular context), then it is a rather weird request. Ignorance is an absence of knowledge. What is the cause for your - most likely - and mine - absolutely certain - absence of knowledge of advanced atomic nuclear plant engineering? Well, there is no cause, you just don’t have this knowledge.
Absence of something that has never existed cannot have a cause. Presumably, there has never been a comet-riding six-headed pink-skinned Elvis Presley, so his absence is beginningless and does not really have a cause, but is Nibbana an absence of comet-riding six-headed pink-skinned Elvis Presley, should we equate them? According to the Buddha, there is no Creator God, so is Nibbana equal to the absence of a Creator God?
I mean, you can pick the absence of pretty much anything (Donald Trump’s intellect, Joe Biden’s honesty, toilet paper in socialist countries, etc.) and then equate it with Nibbana, but is it really productive? Does it make sense?
It is an unfortunate peculiarity of our minds that we tend to view something that is not an object as an object: absence, ‘I’, mathematical functions, etc. You can hardly apply the regular notions of time, beginning, end to these things (see, I said ‘things’ again!), which is why I think the Lord Buddha made the distinction between sankarā and dhammā. Sankharā are objects in a stricter sense, whereas dhammā would be a wider notion including such things as Nibbana or ignorance. The point is that Nibbana is not a thing or place, or sphere, or something existing somewhere or in any time, in the past, present, or future, it cannot have a beginning, end, cause. Neither can ignorance. Or the absence of a six-headed pink-skinned comet-riding Elvis Presley.
Ignorance cannot cloud anything, especially Nibbana, because ignorance and Nibbana are not things.
But then, this is my interpretation. In the more classical Theravadin intepretations, one may agree that, essentially, yeah, the Nibbana element exists at all times and it is our ignorance that does not allow us to ‘perceive’ the Nibbana element or see it with wisdom. They are not the same thing so we should not equate them, but otherwise yeah, your last comment is correct in the more classical interpretation.