Two Complaints of the Nation, and the Re-Appointment of Aharon (audio)

Bnei Yisrael are not afraid to accuse Moshe and Aharon of putting 250 men to death after the test involving the “fire pans and incense” test. Why do Bnei Yisrael fear approaching the holy precinct only after the second test - one with no deaths at all, the one with the flowering of Aaron’s staff?