Do not try to power it on again until you are sure that it is dry. It may not have dried thoroughly internally. A good drying method for electronic units of this type is to leave the battery compartment open, then seal the camera in a Zip-Lock bag filled with rice or desiccant packets which will help to draw out any additional internal moisture in a few more days. When you are sure that the camera is dry, clean the contacts & battery compartment with a little electrical contact cleaner (automotive store), to remove any remaining moisture and help arrest corrosion. Even with the additional time and steps, the possibility of restoring full functionality is only in the 20% range.
Note: Considering the age and present value of this camera, paying the cost of having it repaired , approximately $140 really depends on how attached to the camera you are, but is not cost effective. The standard "rule of thumb" is if the repair cost is greater than 50% of the value of the camera, it is not worth it. A good used or refurbished Panasonic DMC-TZ3 can be purchased for about $45 - $60 and I've seen new ones (open box) for around $99 US
Please keep in mind that my diagnosis & solutions provided are directly dependent on the accuracy of your description of the problem. As with any "do it yourself" fixes, success is a "team effort", since I can't see or touch the camera, and relies on the customer's manual dexterity and ability to follow the instructions well.
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