Bad ground?

-By 'Sounds like corrosion' do you mean the engine turns over slowly?
- Here's a start...
-Make sure your battery is fully charged. Or, pull up a car with a good battery.
-Put on some safety glasses.
-Connect jumper cables (+ to + and - to -)
-Put in 'park' or depress the clutch; Try to start.
-Have someone feel the battery posts while starting to see if they get hot. If so, bad connection- fix)
-Still a problem, remove the jumpers completely, remove the coil wire, hook one end of the red jumper cable to the big post on your starter and the other end to the + terminal of a good battery. Hook the black jumper to the - post of the battery and touch the remaining end to a clean spot on your engine block near the starter. This will tell you if the starter works. Watch out. If the starter works, the engine will turn over. The fan will turn. Make sure the coil wire is removed so it can't start up and take off.
-There are a lot of things that can be wrong but start with this.
-Get back if you're still at a loss.