  We present the detailed analyses of a model of loop quantum Schwarzschild
interior coupled to a massless scalar field and extend the results in our
previous rapid communication arXiv:2006.08313 to more general schemes. It is
shown that the spectrum of the black hole mass is discrete and does not contain
zero. This indicates the existence of a black hole remnant after Hawking
evaporation due to loop quantum gravity effects. Besides to show the existence
of a stable black hole remnant in the vacuum case, the quantum dynamics for the
non-vacuum case is also solved and compared with the effective one.
