Reverse polarity

I know there are hundreds of posts on this. I cannot find my situation. So I had my battery die. I asked someone to take my car to autozone to replace the battery. When they went to leave, the battery was dead so they jumped it, and jumped it backwards. They drove the car, and it drove fine but then lost Engine power while driving. The dash also started flashing all different codes and the lights were flickering on and off.
They called me, I come home. The car wouldn’t go into ready. It only went into neutral, and then would flash “shift to park”. There was an alert “low or high voltage. Please see dealership” and something about the collision warning system being messed up. I put it on the charger to see if anything changed. Well, I let it fully charge and then the car started the next day. I didn’t drive it anywhere as the warning lights were still on. I checked all fuses in the engine fuse box, the fuse box on the drivers side cabin, and the fusible link connected the battery terminal. The only fuse that was dead
Was the engine fuse “ETCS”. It says “engine control, fuel lid opener”.
I changed it, no change in the car.

I went outside today and the car wont start, it will not go into neutral. I can hit power and get it in standby. Then it won’t let me power it off unless I disconnect the battery. I assume this is due to the 12v losing charge from sitting for a week.
What can I check next? I bought a fusible link because I was sure that was going to be the problem. It arrived today which is why I went back outside.

Anyone have any tips? I am on FMLA leave from work until Nov 22nd, and I use my car for work. I have no money for a shop bill and I can’t even go back to work unless this gets fixed.