Nothing you have done should have caused this to happen. To me, it sounds like there is an issue with the electrical box.
Does it still do the same thing? Do the lights turn on and the starter engages when the battery is connected? Also, I want you to remove the starter relay and see if the starter still engages. It is located in the fuse/relay box.
There is also a headlamp relay in the same box. Check it as well.
Here is a link that explains how to check a relay:
I attached the wiring schematic for the starter circuit so that you would have a reference. I had to cut it in half to make it readable, but I did overlap the two so you can follow from one to the next.
Let me know what you find.
See pics below. Also, if the dealer that sold you the vehicle provided a warranty, you may want to contact them. As mentioned, you did nothing wrong, and I suspect the problem is in the fuse box.
Images (Click to make bigger)
Monday, November 20th, 2023 AT 7:14 PM