Why wont power reach my amplifier?

I have a Dual 400w amp hooked up in my Taurus. I have the power wire hooked to my battery and my ground hooked to a bolt in the wall of my trunk. The remote wire I just slid into the 5amp fuse for my radio(used to be hooked to a 30amp wiper fuse but I moved it earlier to test it. Not sure if this would cause any problems but nothing seemed to change when I moved it). Anyway, my amplifier wont turn on(it has a little blue light that comes on when it has power) and I cant figure out why.

I took a multimeter to it and found that my power wire has 13v (w/ engine block as ground) going to the inbedded fuse(on the wire near the battery). The power wire at the spot it hooks into my amp only has 0.3v.(with trunk wall as ground). I’ve checked entire power wire for faults and defects but found none. Is my problem my ground? and if so, where can I find a good ground?

Update: I have tested the power wire on the amp using the gound on the amp(leads to trunk wall) for my negative. only gets 0.3v if I’m lucky. But I’ve checked the same power wire(at a different spot) connecting my negative probe/wire on the multimeter and had significantly more power. Does that make the ground my issue?