  We investigate the interior structure, perturbations, and the associated
quasinormal modes of a quantum black hole model recently proposed by
Bodendorfer, Mele, and M\"unch (BMM). Within the framework of loop quantum
gravity, the quantum parameters in the BMM model are introduced through
polymerization, consequently replacing the Schwarzschild singularity with a
spacelike transition surface. By treating the quantum geometry corrections as
an `effective' matter contribution, we first prove the violation of energy
conditions (in particular the null energy condition) near the transition
surface and then investigate the required junction conditions on it. In
addition, we study the quasinormal modes of massless scalar field
perturbations, electromagnetic perturbations, and axial gravitational
perturbations in this effective model. As expected, the quasinormal spectra
deviate from their classical counterparts in the presence of quantum
corrections. Interestingly, we find that the quasinormal frequencies of
perturbations with different spins share the same qualitative tendency with
respect to the change of the quantum parameters in this model.
