Why won't my 1993 Subaru Legacy start?

I just tried to replace my fuel filter, and could not get the hoses off for the life of me. I disconnected the negative side of the battery, and went under the passenger back seat and unplugged the plug (read it in a forum to unplug white plug and run car to depressurize). After I couldn't get the hoses off, I put the nut back on, re-plugged in the negative side of the battery, and plugged that plug back in under the passenger seat, and now the car won't even make a noise when I turn the key. There is 0 power. What happened?