Cars Q&A

i hav 2002 hyundai sonata gls recently i gav my car for paint,but while taking car back it didnt start,i showd it to wireman n he told ecm box is not working.also he tolod only 2 out of 4 cylinder r workin hence less pickup n engine backfires in lpg. so pls tell me wht is exact reason for ecm failure n is it repairable or wht is cost of new ecm box..thnx