In your question do you mention that your child seems "a zombie" in the morning, yet you say that he wakes up and doesn't fall asleep, no matter what you try. You don't describe other symptoms like yawning, general crankyness, tiredness during the day...
The point is, if a child wakes up after twelve hours of sleep or so:
Did it occur to you that he might simply have slept enough?
There are recommendations as to how many hours of sleep are usual for a child of a certain age, but those are not "one-fits-all" values. Children have individual needs, some will always need more, some less and some will vary depending on what is going on in their life.
For the moment I will be assuming that he gets about the amount of sleep that fits his needs, which means you can only try to influence when he should sleep.
You don't tell much about his daily schedule, whether he's home or goes to daycare, so I'll offer you two suggestions:
- cut the nap
This means he goes to bed rather early in the evening, but might be cranky before bed. This is probably the method most parents in western culture choose. Many children stop napping during their third year, or at least significantly shorten their naps.
- let him stay up longer in the evening
Some children need a nap after a morning in daycare or similar to wind down and regroup. For them, taking a short rest is very beneficial. The fact that your child takes a 2.5h nap at the age of three could be a hint that he falls into that group.
So before you try a "don't get out of bed" light, I suggest you do some basic calculations based on when you want your child to wake up and adjust bed- and naptime accordingly. You need to plan for a certain transition time until the new schedule is established.
Unfortunately children - like adults - have their "internal clock", some will always wake early, others simply seem not to get tired. But if I read your question right, even an hour or two more in the morning is better than having to get up at 4:30... And there are people that simply aren't "hit the floor running" types. They need a certain "get into gear" time to start their day. My daughter is like your child: A zombie for the first hour at least. We adults tend to drink another cup of coffee and muddle through, children are more direct in their feelings. It does get better though...