12V voltage low and then hybrid system malfunction

Possibly. The odds are pretty good.
At any rate, it IS the first thing that you should do.

 

First thing I'd do is take the 12V to a battery shop and see if it can be revived (brought back to life). Don't jump to the conclusion the battery is "dead" and needs to be replaced. That's a lot of money on a hunch. See if it can be re-habilitated first.

 

Contrary to "marketing hype" from charger makers, once a lead acid battery is "worn out", it can NOT be recovered.

Now.....if it is simply low on charge and hasn't been left sitting that way too long, it might just need a recharge.
Might.

Also not mentioned yet in this thread......it also could be a loose or corroded connection at one of the 4 "main" battery cable connection points.