Hello and welcome to JustAnswer!
The underhood lights aren't controlled by a module or anything sophisticated, you couldn't have damaged anything by installing these lights. They receive a power feed and then a ground through the hood switch, a very simple circuit.
Since there is no power to anything on the whole car you most likely have a battery related issue. It could be the battery itself, battery connections, positive or negative cable connections or the cables themselves could be bad.
The first thing I would recommend is checking both battery terminals to make sure they are clean and tight.
If you have a voltmeter take a look at battery voltage. If you don't have a meter try jumper cables or a jump box if you have these available, if not you can have the battery load tested for free at most large parts stores or Wal-Mart.
If the battery and connections are ok then the positive and negative cables and connections should be tested next.
I hope you're right. That would be a big load off my mind. I'll give it a try & get back with you later to let you know what happened. Thanks very much.