2002 Kia Spectra something bad is wrong

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2002 Kia Spectra 4 cyl Front Wheel Drive Manual

my mother in law put a battery in her kia wrong and hooked the cables up wrong the ecu was burnt up so I replaced it with a new one all the fuses and relays check fine but nothing electrical works at all could the wiring harness have possibly burnt somewhere also and if not what could be the problem