  We numerically solve semiclassical kinetic equations and compute the growth
rate of the Dyakonov-Shur instability of a two-dimensional Fermi liquid in a
finite length cavity. When electron-electron scattering is fast, we observe the
well-understood hydrodynamic instability, and its disappearance due to viscous
dissipation. When electron-electron scattering is negligible, we find that the
instability re-emerges for certain boundary conditions, but not for others. We
discuss the implications of these findings for experiments.
