I know this was posted a while back but wanted to chime in because I just had the same issue. I use a Vapor Shark DNA 200 and reciently started using a Velocity RDA. I've noticed on several occasions that it was wet under the Velocity from over dripping I guess. I made it a point to regularly take the RDA off and check for and clean off any juice. Today I vaped it and put it away on a full charge. Came back to it later and it would not power up. The blue LED on the fire button would light but it wouldn't come out of sleep mode and the screen wouldn't light. I just updated to the newest firmware a couple weeks ago becuase it quit working, so it has the most current FW. Today when it quit just for curiosity I plugged in my charger and it powered up and would work fine but if I didn't continue to use it and let it sit for a min or so it would not power up. I took it apart and hosed down the board with alcohol and blew it off with compressed air, hooked the battery back up and nothing had changed. I use a squeeze bottly with my alcohol I I gave the fire button a good second squirt and blew it out and now it works perfect. Guess my issue was juice in the fire button. Hope this helps others with this issue. Cheers, Spanky