In this case the home owner was not aware that the siding had been burnt. It became apparent after pressure washing the siding. Luckily the chimney liner had been replaced before further damage / disaster struck

This chimney is in desperate need of repair. The condition of the flue is unknown and the use of the fireplace could be lethal. That warning might be over kill but why take the chance. Additionally, water will enter the cavities of the damaged cement blocks used to build this chimney and run down the wall eventually finding its way into the wall cavity causing mold, mildew and rotting the wood framing.