welcome to the fest.
now, let's get to the issue. is it not cranking (nothing happens when the key is turned), or not starting (just cranks and doesn't start up)??
they are 2 different issues.
1st, get a fresh battery. then see if it cranks. if not, then look at the starter circuit. you could be looking at simply a atarter, or perhaps an issue with the ignition switch. (or somewhere in between)
if it cranks, then check for spark. if spark, then check for fuel. if both spark and fuel then check compression.
to check spark, remove the boot from the sparkplug and install a spark checker (less than $10.00 for a good unit @ parts houses). or, you could try to hold a screwdriver in the boot and have an assistant crank.
if no spark, then suspect a crank sensor. you could try swapping out the one from the 535, but it could also break, too, so be careful if you do go that route.