WD-40 do make their own brand of contact cleaner…
Well, lookie there. I had no Idea. Hopefully it’s not their old penetrating lubricant in a different can. 
I am definitely going to try your solution. I ordered the WD-40 Specialist Contact Cleaner Spray but I have 2 shows before it arrives. Do you think this might do the trick in the mean time? It’s CRC Contact Cleaner. Thanks!
For the sake of clarity, what did you do specifically when you say you applied contact cleaner to the “power supply”? Are you talking about applying it to the blades of the external power supply (wall wart)? Or are you referring to something internal?
Mine did it again last night before a show, I turned off and on again 2 times and the last time worked. Sometimes the Db meter reading is frozen, but sometimes they read the input ok, though there’s no sound coming out of the quad.
Yeah i have this issue regularly. Its extremely frustrating. I wish NDSP would acknowledge it and hopefully its a software fix…
I solved this by spraying the connections on the Quad regularly with CRC Contact Cleaner. Hasn’t been an issues since. I think that area gathers a lot of party gravy during gigs and needs to be kept clean.