I got some issues with my 99 Lumina LTZ.

so like 2 weeks ago, i reloacated my battery to my trunk. i used 2 gauge wire, and a 150 amp circut breaker. today, i went to start it, it cranked like twice, then i lost all power. luckly my buddy lives like 5 min from where i was and we sat in Menards parking lot trying to figure out what was wrong. finaly, we put the battery back under the hood. i thought that the termal was just loose under the hood where it attatches to the + post, but it was fine. just for kicks, we put the battery under the hood, and hooked up my sub the the 2gauge wire in the trunk and the subs work fine. so basicly im asking why will 12 volts run down the wire and power the sub, but when the battery is in the trunk, i get absolutly NO power to anything??

this is a very sketchy sketch of the wiring lol