  We present a theory for the differential shot noise, $dS/dV$, as measured via
shot-noise scanning tunneling spectroscopy, and the differential conductance,
$dI/dV$, for tunneling into Majorana zero modes (MZMs) in the putative
topological superconductor FeSe$_{0.45}$Te$_{0.55}$. We demonstrate that for
tunneling into chiral Majorana edge modes near domain walls, as well as MZMs
localized in vortex cores and at the end of defect lines, $dS/dV$ vanishes
whenever $dI/dV$ reaches a quantized value proportional to the quantum of
conductance. These results are independent of the particular orbital tunneling
path, thus establishing a vanishing $dS/dV$ concomitant with a quantized
$dI/dV$, as universal signatures for Majorana modes in two-dimensional
topological superconductors, irrespective of the material's specific complex
electronic bandstructure.
