Nissan Silvia 240sx 1996 Indicators & Sterio Fault Please help.

[b18cu]

I am an owner of a 1996 Nissan Silvia 240sx with an sr20det.
I was recently fidling around, trying to hook up my boost gauge light and i think i have blown something but can not determine what it is.
I tried Pigybaking the positive wires from my boost gauge to the main power supply to my head deck and as i was doing so, heard a click and my radio/ clock/ indicators went out/stopped working.
I have checked all fuses with a muti metre and changed one that had blew and found that to be just the clock, the others still are not working. Now whenever i go to plug my head deck wires in the back, it makes a horrible static noise through the speakers and doesn't turn on. My indicators are also not working.
Was wondering if it is a relay of some sort? I am stumped and don't know where to go from here.

As i have said, i've checked all fuses, both at the foot compartment and in the engine bay and all check out fine, even the one in my head deck.

Any help would be greatly appreciated. Thanks