Non-linear I-V characteristics have been measured on high-quality deoxygenated YBa2Cu3O6.4 thin films, in magnetic fields up to 8 T. Critical scaling analysis of the current-voltage data demonstrates the existence of a pure two-dimensional vortex-glass transition with Tg = 0 for high magnetic fields (7, 8 T). The validity of the pure 2D vortex-glass model in our samples is checked with the linear resistivity term and the non-linear current density. The linear resistivity ρlin(T) ∝ exp [ − (T0/T)p] from resistivity vs. temperature and current-voltage measurements, produces the parameters p (p = 0.78 for H = 7 T, p = 0.73 for H = 8 T) and T0 (230 K) used for the scaling analysis. The non-linear current density jnl exhibits a power law temperature dependence jnl(T) ∝ T3 suggesting ν2D = 2 as predicted by the 2D vortex-glass theory. The values of the exponent p obtained in this study are in good agreement with the predictions of the quantum theory of vortex tunneling.