Put the dash back together, see if it starts; if so, good. Now get a voltmeter, and find a wire that only has power with key on, could be the cig lighter. Splice radio into that.
Why is there any "splicing" to begin with? Why not just use the factory connection? If you have a modern unit that needs a full time memory source, just add a fused power wire for it from the fuse box.
