Yamaha Electone HS 6 Mainboard shorted?

[Pigyboy]

Hi,
I am working on a Yamaha Electone HS 6 that had the footpedals plugged in while the unit was on. All the indicator lights went off. I am getting power into and out of the supply and into the rest of the unit. The footpedal connection goes right into the mainboard. Could this have shorted out the mainboard and how do I check?
Thanks