I don’t know what brought this on, but I have been having trouble booting up my phone. The other day it restarted suddenly, and then it was caught in a loop of constantly restarting. I wasn’t able to turn it off or do anything else to it. I waited for the battery to die before I fully charged it. When it was charged, I turned it on and found that it was in Field Test Mode. It took me several tries to get out of it and when I did my phone booted up in Safe Mode. I was unable to use the power button to put it to sleep and there was not dialog box showing options to power off/restart the phone. When I held the power down button, it went back into field test mode; I am unable to completely turn off my phone, every time I hold the power button it restarts. As advised, I made sure the volume buttons were clean and not sticking down, but I am still having these issues.