Clearly something must be wrong with one or more of the hypotheses used to reach this result. It was suggested that one could not simply sum the contributions of each of the concentric shells since stars are not precisely points of light and some of the nearer ones must surely occult those which are farther away. If this be true, then the night time sky would only be as bright as the average surface brightness of a typical star. This helps, but not much. Now the sky drops from being infinitely bright to the brightness of a typical star, say, the Sun.
Lets look at the last assumption by Olbers.
Certainly we know that there is obscuring material in the universe and, at first, one might argue that this material could reduce the calculated sky brightness. This idea is in trouble since any obscuring material, where ever it be located, would be heated by the energy it received from more distance sources and would, in time, begin to radiate energy itself. If the universe is not infinite in extent, then the shells would not be infinite in number and the sky brightness could be reduced. There is no evidence, however, to suggest that the universe is bounded and finite. In the absence of such observations, we cannot be sure that Olbers' first assumption is untrue.