The pink sticker is for the phone company to see that your warranty is now void. this happened to me. best bet is to go to a phone store and ask to try a new battery and see if your phone will work.

So I left my phone in the grass and it got sprayed by the sprinkler system, for a while, because I wasn't aware of it.

I dried it out, plug it in, it starts up fine, but tells me to "Insert battery" even though my battery is in there. I've heard of LG batteries having a water sensor on them but I can't find one on the battery. I do see a pink circle under the battery on the phone back, but the phone is working fine now.

Do I just need a new battery, or is there a secret sensor I need to replace with white paper somewhere hidden?

Thanks.