Car won't start. Sounds like it is trying to turn over but won't start. on 2006 Cadillac CTS

Haven't driven anyplace in a few days. Outside temp is in 40's. Went out to drive this evening and car wouldn't turn over. Electrical system working. No dim lights. CarMD showed no codes. Does not "click" but sort of sounds like it wants to turn over.

Asked by for the 2006 Cadillac CTS