I think your last paragraph sums it up! The symptoms suggest a loss of power to the stepper drivers, which would be where I start looking. Check output voltage on stepper power supply?

I have had a similar problem on my own (home-built) machine which I tracked down to a previously-unseen fuse on the PSU board. On replacing it, I found that the real problem was an internal short in the toroidal transformer.

Classic fault-finding approach (apart from "panic and start changing things randomly!") is to look at what works and what doesn't. Here, we seem to have everything except the actual motors working. None of the axes work, hence problem probably in something common to all of them. None of the driver leds are on which suggests power loss. Hence suggestion to check power supply, is it getting mains power, are there any internal fuses/breakers tucked away in there?