Need a PS script to change permissions on files to inherit permissions from parent folder

Kind of at my wits end here :) I need a script that can go through files in directories on the server and ensure that every file is set to inherit the permissions of its parent folder.

We have software that places files on the server, but the files each have explicit permissions set by the software for system\administrators only. The software cannot be changed to save with different permissions, so we need to do this with a recursive script.

This is very easy manually: right-click parent folder, Security tab, Advanced, check the box "Replace all child object perms with perm entries from this object", then hit OK ... all files in sub-folders receive/inherit those parent permissions. We have a few folders that do NOT inherit though, so we need to preserve those by excluding them from the process.

I am finding this very difficult to do programmatically, however ... I can't seem to get the PS commands Get-Acl, Set-Acl, etc. to actually change permissions, inheritance, or anything really and I'm wondering if I'm barking up the wrong tree entirely and that there is a different way to handle it.

Thanks everyone!