Our sages זצ”ל suggest quite a few possible explanations to the shocking death of Nadav and Avihu while celebrating the dedication of the new Mishkan.
One interesting explanation suggests that Nadav and Avihu entered the Mishkan after drinking wine. This explanation has support from the fact that immediately after the Torah tells us what happened, it goes on to warn Aharon and sons never to drink wine before entering the holy Mishkan.
It is very perplexing, to think that two holy sons of Aharon HaKohen would get drunk – just as they are about to enter the holy Mishkan to serve Hashem?
My father זצ”ל said once : They knew that many of our Mitzvot are enhanced by making a blessing on a “Kos Shel Bracha” – cup of wine, (Kidush, Havdalah, Wedding,, Brit Mila, etc.) and they thought it is the most appropriate way to start serving Hashem, by firstly making the blessing on the wine. Their mistake is therefore NOT that they wanted to drink a “Kos Shel Bracha” and work, rather their error was that Hashem gave Aharon strict rules as to how to serve him in the Mishkan, and it was not up to any individual, even as holy as Nadav and Avihu, to change these rules and to add the “Kidush”, the ritual blessing, without instruction.
Rabbi Chaim Michael Biberfeld