LabQuest is designed to be splash-resistant, but is not waterproof. If the unit is immersed or gets very wet, permanent damage can result. Such damage is not covered by the LabQuest warranty. If your LabQuest unit has gotten wet and now it behaves strangely or won’t turn on, here are a few steps you can try:

1. Do not plug it in. Remove the battery as soon as possible.
    How do I remove or replace an original LabQuest battery?

2. Give the unit at least a week to dry out in a dry, well ventilated area. If you have access to a laboratory grade dessicant or silica packets, such as those found in the boxes of new shoes, you may try placing the unit in a chamber with the dessicant, but be sure that the dessicant does not make direct contact with the unit.

We have seen cases where the above steps have helped revive a unit that was damaged by water. These may not help now, but to prevent something like this from happening again, you may want to see some options for protecting the LabQuest from getting wet in the first place:
Are there options to protect my LabQuest from getting wet?