Best bet is to sort out your Hot (+) and Gnd (-) with a DMM or a test light. It's drawing too much current blowing 200A fuse instantly specially when you haven't powered up the HU. If it's blowing during power up I'd check for remote turn on wires together with speaker wires.
Once again from Basic Car Audio Electronics:
Note on Blown Fuses
When a fuse blows (even one that has been perfectly capable of handling the current requirements of a given piece of equipment), many people will replace it with a fuse of equal size without thinking (which isn't necessarily a bad thing). Then, if it instantly blows again, they go to the next larger fuse size (now, that IS a bad thing). They don't think for a minute that the fuse that just blew was the same as the one that worked fine for a long time. They don't think that something just might have changed which is now causing the amplifier to pull significantly more current.
If you have a piece of equipment (especially an amplifier) that has played fine for a while with a given size fuse and the fuse blows, do not replace it with a larger fuse. I'd actually suggest temporarily replacing it with a fuse ~1/2 the rating of the one that blew. If you have a 200 watt amplifier that's been running fine with a 30 amp fuse and the fuse suddenly blows, replacing it with another 30 amp fuse is fine but I'd suggest trying a 15 amp fuse first. With the volume set to its minimum position, the amp should power up and idle with the smaller (lower rated) fuse. It should also play cleanly at a low to moderate volume. If the fuse blows with no volume, there is very likely a problem with the amplifier. If it does not play cleanly, there may be a problem with the speaker(s) or wiring. If it blows the fuse at very low volume, there is most likely a shorted speaker or a short in the wiring.
For amplifiers... What happens many times is that a component fails (often an output transistor) and the fuse blows. Since the fuse has likely been passing a fair amount of current (remember, the amplifier was playing loud enough to fail) the fuse's element was at a higher than ambient temperature and allowed the fuse to blow relatively quickly. When you insert a new (cool) fuse, it will take more to blow it even if it was identical to the one that originally blew. If the power supply components in the amp are operating at the upper end of their safe operating area (common with budget amplifiers), the new fuse might not blow before the power supply components (remember that the amplifier probably has a shorted output transistor). If the power supply components are destroyed (along with the output transistors), the repair bill may be significantly higher (maybe $100 instead of $60). Checking to make sure that everything is OK with the smaller fuse will assure you that no more damage is done.
