Outer Limits 4x4 Board

in the middle of doing an engine coversion in my gq only just refitted my battery haven't changed loom or anything carby motor. with the key out my handbrake light still works so i just leave the handbrake off but yeah wtf? any idea's don't think its anything with my brake master cylinder

sounds abit like a short to constant power , insted of getting power when the ignition is on get a test light fromt the battery to the switch with the key off if it lights up there is a short .
then the fun part of finding it , could you have damaged the loom at all while doing the swap?