Electricly challenged...Help!

Well look we don't know how you wired it. The dome light is a clue, as I said before. SOMETHING that is DISTRIBUTING MAIN POWER to the main basic circuits is losing connection. This means it has to be close to the battery end of things. Start tracing from the battery......to wherever it goes.........to wherever it goes ........to wherever it goes.........to the ignition switch.......to the headlight switch........and so on.

With modified wiring it will be difficult to help you, unless you happen to have an accurate diagram of what you did

RE RE RE check your battery terminals!!!!