A temp change or sweating should not trip ALL the water indicators on the phone (there are more than one for this very reason).
If all are tripped then the phone has clearly been for a bath !!
The most common one is in the headphone socket (gets wet if using phone in the rain) but this action should not trip all the others.
For the warranty to be rejected for water damage ALL the indicators need to have been tripped, if not, the warranty is still valid.
Anova are notorious for rejecting warranty for this reason and try to use it as a money spinner (search Google for the bigger picture).
It has also been proved on here a few times before so get the phone back and get an official LG service centre to look at it and ask for a report that you can then use to escalate your issue within O2 (as a matter of principle).
LG will likely repair your phone if warranty is still valid so just collect the info together for your complaint.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
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