I'm not sure if this is related or not but I figured I'd get some input from other people and might as well start from the beginning.

I've had this Clarion MAX-685 (I think that's the correct model number) double din unit for a while now. When I originally put this in I had the video feature wired up to a switch and then two 13.5" JL's in the back. There were no problems for a while and then after a few months the video stopped working so I figured a wire on the switch came loose but I didn't really care cause I rarely used it.

About 3 weeks ago now I decided to tear it all apart and solder all the wires instead of those little crimp connectors. At the same time I fixed the video switch. During my test to see if the switch was working I tried turning it on and it shorted blowing the fuse. Decided to finish soldering everything and put it back together then replaced the fuse. Everything worked great including the video and I had no issues until about a week later.

Driving home I pulled up to the garage and stopped to wait for the door to open. When I went to drive in the car had entered limp mode and wouldn't get any power from the throttle and basically just idled itself into the garage. If I put it in park or neutral it would rev just fine but in drive or reverse there was nothing. I turned the car off and tried to turn it back on to see if it was fixed but the battery was completely dead, couldn't even roll up my windows. I knew that the alternator had been going bad so I figured it was shot and ordered a new one.

Replaced the alternator and charged the battery on a trickle charger until full and then everything was fine again for about 5 days. Then the same problem, stopped at a stop light and when I tried to go it was in limp mode. This time I left it on for a bit and it would never fully die but all the lights would dim and then go out and even the head unit turned off entirely.

Yet again I charged up the battery and then this time I tested it at advance auto and their tester said it was a good battery. Around this time I picked up a new G that is a 6mt and the auto is now my girlfriends so I really wanted to fix it. I'm planning on taking the Clarion and putting it in my new one but haven't had time so instead I pulled the radio fuse and let her drive it around for a while. No issues for over a week then yesterday it entered limp mode at highway speeds. Something is obviously still wrong and same thing, battery totally dead.

I know this is a long post but I was trying to give as much background as possible so my question is this. Could I have a wiring issue from the stereo that is draining the battery so bad and it still does it with the fuse out or is there some other crazy electrical issue?

The only thing I've worked on in the last 4-5 months was the stereo, other than changing the oil. I went and talked to a nissan tech but he had no idea and really just looked like he didn't know how the electrical system worked in general.

Oh and also the battery is an Optima redtop if that helps and it tested at a little over 14 volts and 770CCA right after being taken off the trickle charger. Could it have tested good but really has a parasitic drain in itself?

This is just really frustrating because I don't have any electric testing tools so I'm not sure what to try next. Any help you can give me would be so appreciated you have no idea. I want her to have a reliable car so she doesn't get stranded, especially since she helped me get the 6mt Hopefully I didn't leave any vital information out but if there is anything else you need to know let me know.