hood won't open

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. Here's a directory link for you: http://repairpal.com/cadillac-repair-in-minneapolis-minnesota

You could also try lubricating the latch with WD40 and try working it loose. If that doesn't work take Superbob's advise.