The problem with the Necrons is that they feel really weak overall due to their design. Their strengths have been translated in a way that makes them into liabilities rather than strengths. The reduction to points cost is an inappropriate buff to them that fails to address any of their weaknesses, which stem from their implementation.
The following changes, in my opinion would make the Necrons a much more fun and competitive race to play as and against:-
1. Necron Regeneration
Ideally: Necrodermis is supposed to be an immensely strong material that can regenerate damage within moments. This means that the Necrons shouldn't in theory require a shield since their hulls are innately very durable and can regenerate.
Reality: Necron regenration is actually a much worse ability than standard repair. And practically useless in battle.
The lack of shield means that Necron ships are very easy to cripple with critical hits, and by the time they would regen these hits (60 seconds) the light critical have turned into the more permanent severe critical hits and can thus not be repaired. Since there is no shield, the criticals just go from bad to worse without any actual opportunity to repair.
Solution: Reduce the time taken to heal light criticals to 10 or 20 seconds. Replace the (unused and useless) hull cauterization stance with something more useful. I would recommend removing the scarab swarm as an ability and turning it into a stance for all Necron line ships; when in this stance, the Necron ships would be unable to fire, but instead project a scarab swarm that damages nearby enemies and heals damage on nearby friendly ships (including light critical hits).
2. Inertialess Drive
Ideally: The Necron inertialess drive combined with their teleportation meant that Necrons, while seemingly slow, could be very manoeuverable when needed since they could teleport their ships and turn their ships on a dime (by negating their inertia).
Reality: The inertialess drive ability feels like a teleporter that can't really keep up with other races. While their actual movement is very sluggish and doesn't match the supposed high manoeuverability of their
Solution: Rename the current inertialess drive to something more appropriate (such as "mass relocation" or "teleport") and either increase its range or decrease its cooldown.
Add in inertialess drive as an attribute similar to plasma drives for human ships; the inertialess drive would allow Necron ships to turn extremely quickly and change their movement vector without needing to turn in a circle (as if they were not affected by inertia/momentum).
3. No Shields
Ideally: Necron ships are extremely durable and can regenerate; they therefore have little use for shields and are just as effective without them.
Reality: The lack of shields makes it trivially easy to cripple Necron ships using critical hits (which they take much more easily than others) and lightning strikes (which they have no defense against). It's just sad when you watch a Cairn ship go from full health to useless hulk within seconds due to a combination of lightning strikes and destroyed components.
Solution: Necrons need a way to prevent critical hits and lightning strikes. This one is beyond me, since it ties into the wider problems related to the instantaneous nature of the boarding mechanic. Perhaps Necron ships could be immune to lightning strikes unless they are at low health.
4. Gauss Weapons
Ideally: Gauss weapons are terrifying due to their accuracy and ability to completely ignore armour by taking apart their target at a sub-atomic level.
Reality: Gauss weapons feel pretty weak; they're accurate, but that doesn't make up for their weakness against armour (the opposite of what they are supposed to be).
Solution: Make gauss weapons have a heavy armour reduction effect, since they are supposed to be weapons that are not even affected by armour.