You can read about it in the SC's
short order here. But to give you a better picture, here's what I can see - and the read of that of most qualified people - not just amateurs like you and I:
PTI leaders had in the run up to this made a few attempts to misapply the constitution, prior to this they were also arguing for preventing an NVC by pre-emptively disqualifying candidates or not counting their votes afterwards, neither of which is prescribed.
As per the last reference to the Supreme Court, the SC's opinion said that the NVC must go on as per the Speaker's Constitutional mandate, no later than 3rd April. He violated this mandate and the explicit advice of the SC Opinion to respect this and conduct the vote by frivolously and incorrectly applying Art. 5 to dissolve the assembly.
Opposition lawyers, Pakistan Bar Council and the SC Bar all made solid arguments against this, the court also felt that Art. 5 was applied without any pending case against members or the house. The repeated delay tactics and this last attempt to stop the vote is why the SC explicitly ordered voting to commence no later than the 9th of April, and must be the first item on the agenda. Compounding this, a PM who's subject to an NVC cannot ask the President to dissolve assemblies, which IK did and it was clearly premeditated.
Due to the nature of the actions of the Deputy Speaker, are called in legal terms a "nullity", meaning anything happening afterwards is void. It's why in the short order, SC keeps using the term "In consequence of the foregoing, [...]", before commenting on what is explicitly voided.
What's funny is, immediately on the day this happened I said on the forum that "it's not over yet", and that SC will likely take this case up themselves because of how much of a gross and egregious violation of the constitution the Deputy Speaker's actions were. People here were busy celebrating and cackling at us contrarians while fawning over the genius of IK. Sure enough it wasn't genius, and the
court took notice. Meanwhile, some were making the incorrect argument that the courts can't interfere with the NA due to Art. 69 procedural independence. Not realising that:
A) Article 69 is qualified by Article 67, and therefore subject to the rest of the constitution.
B) The Court can intervene, the last time the court directly did rule a Speaker's actions as "justiciable", were in the last parliament, when Imran Khan himself submitted a reference when he was pushing for NS to be disqualified.
Furthermore, although I don't think the court commented on this because they take an apolitical stance and cannot comment on intent, but the whole affair was clearly based on mala fide intent, it was premeditated to prevent the vote, the Speaker/Deputy cannot issue a legal verdict on the legality of a motion in the NA, that's not within his power at all.
Small disclaimer at the end, I am not a legal export, not trained or educated in law. I just followed the hearings closely and repeat what I heard from legal experts and the court itself. Frankly, for this case, you DO NOT need to be legally qualified to know the answer. It was bloody obvious that the court had to take notice and that the inevitable verdict would be thus - it was an open and shut case.