I have a Landmaster TW-400 UTV with Honda GX390. An idiot installed a new battery with anode on the wrong side. Another idiot (me) attached charger cables, essentially reversing polarity and left it on for several hours. Now the engine cranks but produces no spark. It’s not the spark plug or the oil sensor. Assuming the ignition coil is OK (I’ll confirm tomorrow) what do I check next?

Generally, the coil works or it doesn't. 
 
That is, with all safety switches disconnected for testing purposes.
 
Un-plug the thin, black kill wire from the coil and re-test looking at the spark plug for spark, grounded to the head.  
 
 
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