2004 Porsche Cayenne - won't crank - messy wires

[Rachel Walters]

Hi guys. I bought a 2004 Porsche Cayenne turbo. Two days after buying it I drove a mile from the house, turned it off and it wouldn’t start. It was cranking over but nothing. The radio sometimes wouldn’t come on. I finally got it started and drove it home. It died a couple times on the way but started again. After it got home I got a new battery for it. The error went off PSM and it started running. All was well for 1 drive. I took it to the auto parts store and checked for errors and there were none. Before the new battery the error was P2403 Evaporative Emissions System Leak Detection Pump Sense Circuit/Open.
The next morning I go out to start it and it won’t even try to crank. All electronics come on but it says press brake pedal, even though it is being pressed. The fuses seem good and the starter fuse relay seems good. I checked the 2nd battery and it had some corrosion so it was cleaned and a giant fuse was replaced. (Sorry I don’t know all of the technical terms.) If I turn it over sometimes it will turn on the display and sometimes it is blank. The engine fans will come on without it being started and even stay on after the key is taken out. (The battery is being disconnected while we are not working on it for this reason.). The wires under the dash look like a hot mess to me. There is a brown and yellow wire that seem to just be cut. There is a black plug that is not plugged in (has been like that since I bought it.). On the right side it looks like there is a bad wire wrap job.  When the key is turned on sometimes now I will hear a click from a fuse under the seat and all electronics will turn off. When she ran it was great. With all the things going wrong I can only assume this is electrical.
I have no idea where to go from here. The mechanics here can’t look for a couple weeks and only 1 will touch this thing.

I posted images on another forum but it won't let me add them here.  

[GSpence2]

Yikes 😳 

You really need an independent that knows Cayennes has the correct scan tools a lot of patience and a fat check book

Sorry this happened to you