Okay, removed the battery which was now dead and let it charge all day. Checked good, replaced in vehicle and when I connected it (positive first, ground last) the ground connection sparked a lot while attaching - in my mind indicating a short somewhere. Tried starting and it started just fine, but immediately started to smell like something electrical burning. Shut down and disconnected battery. Battery still tests good. Any ideas where I go from here?

As to queries as to why I replaced the battery, it was 7 years old and it was having problems holding a charge. Car was running fine when battery replaced.