Typically

When do the drum brake job, the shoes should be replaced and the drum should be either resurfaced or changed. This is because the labor is more expensive than the parts in general. I am not sure it is park brake issue, most likely the drum and shoes has been damaged already. I think the problem is still related to the replacement of cylinder. Perhaps the dealer did a awful job on installing the brake (drum brake has many parts and needs more skill to install).