Cable not working..got new box..all connected..can hear box running..tv has snow

Tv has snow after hooking up new cable box..originally tv sound in and out..picture as well..then box wouldn't come back on..now all snow on tv..upstairs tv comes on..gives cable connection error..is this due too main box /tv not working..main tv on set up want let program channels auto that is saying erased..do I need a new main tv..don't know what to do..have unplugged ..reset all etc..help!!