Every source of light we know — the sun by day, the moon by night, the fire in our homes — none of these can illuminate the supreme abode. That place is self-luminous. It does not need any external light because it is the source of all light.
Consider how the sun is so bright that it blinds the eye, yet the sun itself cannot be stared at. The supreme abode is something like that — beyond the reach of any created light. It is an inner radiance, not an outer one.
And once a person reaches that place, there is no coming back to this cycle of birth and death. That is the mark of this abode. Krishna calls it 'my supreme dhama' — his own dwelling. It is not a location on a map. It is the presence of the divine itself.