Maybe the cable is broken or the latch is stuck. A mechanic could get the hood open and see if the cable and latch are OK.
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http://repairpal.com/cadillac-repair-in-minneapolis-minnesota
RepairPal Certified shops can diagnose and repair your 1993 Cadillac DeVille. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.