S14 SR20DET no power. help.

[94silviaS14]

Alright, first off I will say i have been on this sight for quite some time, just never posted much. Anyways, I have a 1994 Nissan Silvia K's. Recently I installed a boost gauge, the power, ignition and negative wires are tapped into the radio harness. The one white wire for "small lamp turn on" I ran off the rear defrost positive lamp turn on wire. (also just did a FMIC install and relocated the battery to my trunk). Everything ran fine. Gauge worked good. Drove around a bit, then got home. Tried starting it again to go out and everything turned on went to turn over the car... and nothing... no power... no lights... no radio... nothing. I thought my battery was dead so, tried charging that... nothing, tried re grounding my wire in my trunk... nothing... pulled every fuse i could in both my fuse boxes and everyone looks good. Checked all my connections i did when i did my FMIC install and all were good. The only other thing i can think of are those big fuses you can't see into? In both the engine bay fuse box and interior fuse box. I've tried searching what those are in the interior panel, and can't find anything. I let the car sit for a bit and some how my lights came on when i opened the door, tried turning the car on, but everything went dead again. Any suggestions? Any help would be great.