Electrical problem

This is going to sound bad but I'm far from a mechanic. Is the diagnostic port the thing you plug the code reader into? Also is the G200 a black wire? If so is it a thicker gauge wire than say a stereo ground wire? Sorry my skills stop at brake pads and oil changes.

Is the G200 in the first picture? If so every thing is bundled together and looks tight and clean. Also in the second picture the controls for the fan and heat and AC don't work at all and neither do the dome lights. The radio always lights up but only actually works sometimes. The buttons above the controls work fine and so does the power outlets below. Could the radio be a separate issue and a big fuse under the hood be blown. If so does anyone know what ones I should try? And if it isn't a fuse what could be wrong. I'll take all the feedback I can get it's cold in Ohio I need my heat. Thank you!

Yes they stopped working at the same time. The only thing that I did to the car was take the stereo out to make sure the wiring was all good behind it because it wasn't working every time. Upon inspection I found that 2 black wires were spliced but taped back together and also 2 red wires with an orange stripe were also cut but taped back together. All were starting to come apart so I took them all apart twisted them all back together nice and tight and retaped them. I didn't change anything or do anything else. The battery was disconnected while I was doing that as well. Thanks