I can't say with certainty but this passage from A&C appears to indicate the sign was electronic rather than battery powered and was turned off to save energy (again suggesting that is was powered with electricity). But rather than just being your usual contrarian ...... self, why don't you contribute something of substance to the discussion if you know differently?
I'm not the one who thinks namecalling constitutes a rebuttal to anything -- that would be you. You're the one making an argument completely based on an assumption about the Hertz clock that you have
no evidence for. Which is pretty much the case for all of your assumptions about this case.