  Black holes modeled by the Kerr metric are not semiclassically
self-consistent at or below the inner horizon. The renormalized stress-energy
tensor (RSET) of a scalar quantum field in the Unruh state has been found to
diverge at the Kerr inner horizon, causing the geometry to backreact in a
non-trivial way. In an effort to understand this backreaction, here the
inner-horizon RSET is computed for the full physically relevant parameter space
of black hole spins $a$ and polar angles $\theta$. Then, the backreaction is
analyzed using a framework for the dynamical behavior of mass inflation from
continued accretion. It is shown that the initial backreaction from the RSET
does not evolve the spacetime toward any known regular or extremal
configuration, but instead it brings the local interior geometry toward a
chaotic, spacelike singularity, classically stable over astrophysical
timescales.
