Replacing the seat knocked the positive wire from the solenoid lose, and kept draining the battery. Repaired the connection and secured with electrical tape.
Best way to figure out if this is the issue is to attach the black probe of the multimeter to the negative part of the battery, and the red probe of the multimeter to the negative part of the solenoid.
Try to turn the bike on - if the multimeter isn't showing any volts, the circuit isn't complete.