Hi, so i "seemed" to have the same issue as most of you. volume down didn't work sometimes randomly going off by itself then after i reset safe mode activated and i could not turn it off. Tried all the tricks many other forums and suggested pages all failed. So i decided to do what some of you have done. Open it up exam motherboard and possible faulty wiring etc... I noticed the antenna board had some mild residue on it I de-attached it before attempting anything else turned it on without the antenna plugged in. Turned it back on and it worked! Cleaned the antena board with some rubbing alcohol and and q-tips put it all back together and it DID NOT WORK! Confused i reopened it and thats when i realized the first time i also had unhooked the speaker/headphone piece that covers the antenna board. I removed the speaker/headphone piece and turned it on again. Worked perfect once again! I inspected the piece for several minutes until i had the thought possibly water got into the headphone jack itself and was corroded on the inside where i could not see. Finally! A few toothpicks/q-tips and some rubbing alcohol with some patience cleaning and drying it out (after i cleaned as well as i could i let it sit for 20 mins) put it back together turned it on and worked perfectly. Reset it 10 times to verify it was fixed and still no problems! I assume the entire problem was in the headphone jack but in case it was multiple issues i included all that i did. You could easily text the headphone jack theory without opening your phone any more then to remove the battery. I hope this was helpful and solved this incredibly frustrating issue for everyone else!
Soleoe, you are the man! It was exactly the same situation with my chinese phone Doogee DG450. I droped it during the rainstorm for a ~2 minutes, until I found. At first it looked like it's working, but later this problem occured. My Volume Down button didn't work and after restart phone was turned into "Factory Mode" full of chinese text. And when I pressed Volume Up, it was started continuously going down through the list. I opened this part where antenna is and cleaned it with vodka (yea, I know, I didn't have anything better
).
And now it works fine! Just one little problem... during the antenna "plate" opening process I accidentally broke wire which connects these both parts... So be careful.
Once again, thanks a lot!