I'm an idiot in need of help

Can you go into Accessory mode (hit the Power mode without foot on brake) and get the various 12V systems to boot up? Dashboard, audio, NAV, lights, ventilation, etc.? If the fusible link is properly replaced, all or most of these should still work.

 

Fuzzy mentioned the fusible link and i would start there. You replaced the fuse at the battery (was it blown?) but the fusible link is under the hood by the jump points. That strange piece of stamped copper. Measure the resistance between the ends and see what's up.

The car generally tries to protect itself so hopefully that is all it is. But there have been cases where the link doesn't blow fast enough and thats multi-thousand dollar damage to lots of systems.

I would strongly suggest investing in "smart" jumper cables. I am a strong advocate for them. This is the model I have from 6+ years ago, they may not make them anymore, I don't know:

They connect dead, and after everything is connected then they test polarity and connect automatically. No sparking, no way to reverse the leads, and if something terrible happens and things short, the "smarts" fry first not the car. Worth every penny and the LEDs are super nice.

 

The 12 may be dead or the fuse replacement not done well.
Easy way to check is with voltmeter across underhood jump points.
If good there check in that fusebox the jumpoints are in
Usually try big one under the clear plastic opens up.
If 12 good there and no fuses blown usually the Inverter is blown and
Has to be replaced,
Seen that many many times here over 10 years.

 

Then I very strongly suspect something is still not fixed in the 12V system. Don't think about a new inverter yet, get all the 12V stuff working first.

Do you have 12V at under-hood jump points? At the many fuses in the fusebox?

 

Look at the fusible link assembly located within the large relay/fuse box next to the inverter. The fusible link is housed in a 5" long plastic box with a clear cover and whitish sides. Use a flashlight to inspect the DC/DC fusible link. If it is blown you need to replace the entire 5" box - which is not particularly easy to achieve as the large relay/fuse box has to be unbolted to gain access to the underside.

If that link is OK, check the DOME fuse.

If that fuse is OK and you still have a problem, remove each fuse, one at a time, and measure continuity across the fuse, using an ohmmeter. Do not rely upon visual inspection.

If the fuses are OK (check the fuses in the fuse box under the driver's side instrument panel as well) then you probably have to replace the inverter.