92 Camaro turns over no start

I have a 92 Camaro, 305 RS. History- While changing sparks plugs my rachet briefly touched the postive post on the starter. I then disconnected the positive side post of the battery and finished the maintenance. Car started easy, idle nice, all gages looked good. However, "service engine soon light" came on after about 20 seconds. Drove the car for a day without any issues. Bought a hand held code checker, book said disconnet negative battery post for 15 seconds to clear codes. Did that, reconnected battery, and now car wont start. It turns over and code now reads 12 Diagnostic Mode- No distributor signal to ECM. Checked fuses under dash, all good. Any ideas, this has to be something simple??? Appreciate the help,
Steve

Check for spark, i bet there is none. When your ratchet shorted to your positive battery cable, it probably fried your ignition module which is located on the distributor. Find a scrap yard dizzy to swap in, and try it.