It sounds like all of the holds in those final seconds were due to problems with the launch structure and ground systems, not the rocket. It was the same thing with the scrub of Artemis II. I don't understand why ground systems seem to be the source of more scrubs than the rockets, which I would assume are much more complex?
A lot of complex stuff happens in the ground system.
It is dealing with a massive amount of propellants that have to be delivered rapidly and safely to the craft… propellants that are cryogenic and generally hard to handle and maintain at the needed temperatures / densities.
Additionally a range of inert gases have to be used to chill and purge all of the complex plumbing on the ground and on the craft. It needs to keep the propellants pure as possible in the process (prevent unwanted gases mixing in, etc).
It also has to support the craft during all of this, detach from the craft at the correct times using complex mating ports that have to deal with electrical, hydrologic fluids, cryogenic inert gases, and cryogenic propellants, etc.
You also have the deluge system that requires a massive amount of water driven at very high pressures, etc. (actually gas generators built from a set of Raptor derived power heads, rocket engine pressuring the deluge system).
Then in the case of SpaceX the ground systems also have to deal with recovering the craft stages.
Anyway the ground system is often the most complex aspect of a launch system or at least one par with the craft itself.
In the case Artemis they are dealing with low cadence of launches with long gaps in ground system use which impacts repeatable reliability. Also hydrogen fuel sucks to deal with.
In the case of this launch they are dealing with a brand new ground system and tower. It will have teething pains for the first few flights.
…a lot of values, a lot of actuators, a lot of plumbing, a lot of monitoring systems, storage tanks, etc
