It is likely that oil or butter spilled under the reservoir and got onto the heat plate. With LEVO fully cooled down and the reservoir drained, remove the reservoir from the unit. Any excess liquid/ residue still on the heat plate can be wiped away and cleaned with a damp cloth.
Never pour any liquid inside the heating chamber to "rinse" it without the reservoir and nozzle installed securely in place! Otherwise, the liquid will leak through the drain valve and reach the electronics inside of the LEVO. Instead, wipe away any liquid/residue using a damp paper towel or cloth.
If a large amount of liquid spilled and started to leak out of anywhere but the drain funnel, check out LEVO I: Leaking from back panel or base.
If you are still experiencing trouble with your LEVO you can submit a warranty claim here.