2001 Cadillac DeVille DTS

So I just bought a
2001 Cadillac deville
the only key it has is
the valet key. I can't
get the car to start or
turnover. I replaced
the battery and all the
lights turn on and the
bells ding and the
radio turns on. But I
can't get the car to
start or turn over. The
security light on the
dashboard is on then
it goes off. The rear
fuse panel
underneath the
backseat has no
cover so I can't find
where are the ECM
fuse is located. Now
the car is on the side
of the road I can't get
it to start and I just
need to get it home.
I'm pretty sure it's the
vats security system
that won't allow this
car to start. I can hear
the fuel pump and the
fuel injector running
but no power to the
starter. Any
information anyone
can give is much
appreciated thank
you.