HELP! Electrical problem

We recently replaced the dash panel and now I have an electrical problem that I can't figure out. Everything appears to be wired exactly like it was prior to removing the panel and it corresponds to the wiring diagram in the ref section (as far as I can tell).

My problem:
We were water testing the boat on Saturday when I heard something and the gauges all pegged. I immediately shut down and switched the battery and all accessories off. We were able to re-fire the boat after looking for anything major. Once started we noticed we had no gauges. Now, with the ignition breaker on, when I push any other breaker/switch that draws current (blower, lights, etc) the gauges all peg. When I push the horn button the gauges peg.

What I've done:
I've removed all the indicator lights on the dash (these were the only electrical items touched when we removed the dash), I disconnected every wire from the grounding block. Nothing changes.

Other clues/findings:
-There was a draw on the battery before the problem showed and I had a dead battery in about a day. I know, I should have chased it down then.
-We ran the boat for about 45min on the fake-a-lake prior to the water test. Other than the voltage gauge showing low voltage (about 12V at idle, would climb to 15+ at speed) the boat ran fine. Boat will still fire and run, just no gauges.
-The purple wire on the dash(switched power) actually shows ground at the indicator light for the breaker. When I use the test light on the indicator light wires many of the ground wires show power.
-The alternator was slightly warm for some reason tonight, I removed it...no changes.
-I see no burnt wires nor did I see/smell anything electrical when the problem popped up.

I expected to find something simple/stupid that we did to cause this but I can't seem to locate the issue. I'm not really that good at diagnosing electrical problems so once I get passed the easy stuff I'm lost. I have borrowed a multimeter, but have no idea how to use it or what to look for with it...most of my testing so far has been with a generic test light.

I have 10-12 ppl coming into town this weekend and had planned on having the boat done. Any help is greatly appreciated.

-Ryan

Nothing in the gauge cluster was touched, but I'll take a look and see if maybe one of the terminals has come loose.

Alternator is brand new, as is all the main power/ground wires.

Ryan, from all that you've described it sounds like you have more than one problem. One thing I think I can pick out though from what you are saying is that you are missing a ground. You should never be able to read voltage (any measurable amount) on any ground wire. That is of course with the common lead attached to the negative battery post or engine block (that should be your reference). That being said, you have a disconnected ground wire that should come from either the engine block or the negative battery post to the dash. Or maybe this wire is burnt. Either way, it sounds as though you are not getting ground to your gauges. I don't believe this is the cause of your battery draw though. Something else is causing this issue. What kind of a sound did you hear?