Thank you for your post, friend!
I understand that your Frigidaire washer will not power on and you have replaced the black box. If your washer is not receiving any power it could either be an issue with your power cord, control panel, or in home circuit. I would suggest making sure that your household circuit breaker is not switched off or shorted. If the circuit is working properly I would recommend having a professional technician come out in order to provide an accurate diagnosis. If you do not have a professional contact I would check your manufacturer's website for additional assistance. I hope this is helpful. -Matt