2003 Mercury Grand Marquis Crank NO Start. It’s never the ECU!! No codes!!

This was a phone call to come out and program an ECU for a crank no start. So I installed the ECU programmed. It learn the Pats system. still a crank no start. There was no check engine light. No fault codes.  noted actual values, no RPM signal. that’s where I started, the crankshaft sensor at high resistance or an open. Replaced , vehicle started.