I have a Snapper RE - 28" with 12.5hp B&S. I bought it at an estate auction about 2012. LIke new back then - the tires still had all the 'hairs' on them from the molds. Came with the plastic grass catcher.
No battery in it. I pulled the rope a little to make sure it wasn't stuck and had...
As many above have said, clean cable ends. My theory of small engine work, and I admit, I'm an amateur is to start with the easy stuff first. You could replace all the parts and have the same problem if the battery cables are corroded. Clean battery terminals and cable ends with the battery...