How I got my LG Optimus LG-P509 OUT of Safe Mode
First let me say that I got it into safe mode while driving by dropping it into a partial (thank God) glass of diet soda up to just above the bottom of the screen. Twice! (Don't ask!)
If the glass had been full and gotten into the screen area, it probably would be toast.
The first thing I did after pulling it out of the liquid was to pull out the battery. No fancy "shut down" - I just yanked the cover and took it out!
Then I held the phone vertical and started smacking the bottom edge of the phone against my thigh to force the liquid down and out the bottom as much as I could.
When I saw that the wet spots appearing on my pant leg were getting almost too small to see, I then pulled out the SD card and the SIM card.
Luckily there was no moisture on or under either of them, and no evidence it got into anything but the area of the 4 bottom buttons (switches).
I then put it all back together and powered it up.
It SEEMED pretty good, but it was still coming up in safe mode despite multiple hard resets (pulling the battery & waiting 15 seconds) while driving.
So then I just left it apart until I got home. And worried...
When I got home, I looked over a lot of discussions online about how to fix this.
It was stuck in safe mode, and when I hit the menu button, it was like holding the volume up button, and some of the other buttons didn't give the result expected.
When I looked at the application menu, only system apps showed, not any of the apps I had downloaded. But any downloaded apps for which I had icons on the home screen were working. I could not add icons expect for system apps.
But try doing much without using your menu button!!
None of the online tips fixed mine, but many did offer information that would prove helpful later. One example is how to get your phone INTO safe mode:
You shut it down, pull the battery, wait 15 seconds, put the battery back in, hold the power button until it starts the boot-up sequence (you see the LG logo), let go of the power button, then press and hold the menu button and keep holding it down until the phone comes up to the home screen.
If nothing else, this told me that key combinations were "secret" codes.
Being an experienced electronics technician, I was confident enough to take actually my phone apart. (It's out of warranty.)
I did that and wiped off any moisture I saw, and then blew it out with canned air, making sure to hold the can upright and clear the nozzle a bit first, both precautions being done to be sure no liquid came out of the can and got into the phone.
Then I tore it down further and CAREFULLY cut tiny slits in the bottom switches' protective plastic seals to allow me to blow out the bottom four switches, too.
Then I put it back together and tried it again, but it was still in safe mode.
So I lived with it for a day or so, trying off and on to reset it. Then I stumbled onto a combination that worked for me.
With the phone on, I found that if I hold the volume up button and quickly press and hold the menu button, then quickly release the volume up button, then menu would come up! (Did I say "quickly"??)
It takes practice, but that kind of sequence (possibly with different buttons, depending on which of yours got wet) will help you.
Then I realized (hoped, anyway) that I knew how to get it out of safe mode.
I did a normal shut down, pulled out the battery for 15 seconds, then put the battery back in.
Then I held the power button until the LG logo came on, then let go of the power button and held the volume up button down until the home screen came up all the way, and as it did, I could see it was out of safe mode!
My buttons still don't all do what they're supposed to, but I can get done what I want to, and hopefully soon any crud that's still in there will soon either dry out or get pulverized and stop interfering with normal operation.
Hope this helps you!