Total energy of the electron in hydrogen atom above 0eV leads to

The fact that the electron's total energy is negative suggests that it is linked to the nucleus. Its energy levels are quantized, or can only take certain values, when it is attached to the nucleus. But, as soon as the electron's total energy reaches zero, the electron is no longer connected to the nucleus. It is not drawn to the nucleus in any way. Hence, the energy of it can have continuous values. Hence, continuous energy levels result from an electron with zero total energy.