The effect of an applied bias on transport through an electron billiard is studied by analysis of magnetoconductance fluctuations. It is shown that at low bias, nonlinear effects are well-described by electron heating alone, while at higher bias (V > 2 mV, or approximately 5% of the electron Fermi energy) non-equilibrium effects become significant. We chart this behavior by examining the effective electron temperature plotted against the empirical parameter Q (average energy level spacing over energy level broadening) and the spectral scaling exponent alpha. The high bias data shows a departure from a curve composed of lattice temperature data for the same device, which indicates a change in electron dynamics within the billiard. Published by Elsevier B.V.