Hi Q.
You might want to send your question to Kemper Support to get some expert guidance.
Get a few pound of rice (o r silica packets), put your stage in a large bag and cover it with the rice and seal it. Let it set for 72 hours. Works on submerged cell phones.
My Kemper Power Rack is out of warranty, but being the repair guy I am. I would 1st consult with Kemper before deciding to open it up and clean out any moisture or residue. Kemper has always strived to provide good support, so consulting with them would be my first choice.
Congratulations and now the riff to Aqualung is in order. 
That's a great result! Nice work everyone!
I went white water rafting once... with my cellphone left in my pocket and a few flips, so I know first hand that rice works. Silica packets would have been better but I couldn't use my phone to order them while on vacation because it was... soaked. 
