2002 Kia Spectra want start and backfiring.

Replace a timing belt on a 2002 kia spectra 4 cylinder engine, was driving down the highway the engine just cut of so took the timing belt cover of and the timing belt was half way of the sprockets, when cranking the engine sometime it backfires, when the engine cut of driving will the timing belt hurt anythings are will it damage the valve how can I find out have it done any damage.