Power button cycling and volume down not working, otherwise seems fine

Yesterday, some coffee spilled into a tray in which my iphone6 was placed. The power button was inoperable when pressed, ie physically/mechanically , but began acting like it was being pressed sporadically (so I could not fully turn it off because if I turned it off via accessibility setting it would turn right back on). The frequency of the "pressing" increased as the day went on (again, not physically, just electronically). The volume down button also did not work. Otherwise, the phone was fine. Eventually, the battery died and it is now in a bag of rice. Any diagnostic and/or repair suggestions? Thx in advance.