A lot of electrical issues

Just got my new Ip 37 in the water. As of last night all the instruments worked except the autopilot and navdata since the survey. Last night we ran the engine for an hour with the instruments on and everything was working great. Today the mast went up and I connected the raymarine st60+ and that's it. I have to rewire the mast and anchor lights since I changed the plug from what was on here originally.

Now I go to turn all the instruments on and I'm
Not getting power to any single instrument in the cockpit. Any idea what the problem may be?

Update. So i Kept blowing the 15A Fuse on the control head of the Raymarine ST6001 Autopilot unit. I ended up removing every component attached to it until i had nothing left to remove and the fuse still was blowing after i applied power to the head unit. I am guessing the head unit is having some major issues. I removed it and will have to ship it back to ray marine which will take 4-6 weeks apparently. Really upsetting since i was hoping to enjoy the boat in the next few weeks.

It could be the voltage drop between the batteries and the head. Consider looking at where the head is connected and ordering battery cables of the appropriate link to a positive and negative bus and hooking your head to that. I'm not sure that would fix the problem but even if it does not you'll have better power flow to the head.