Q: My iphone 6s restarts in logo screen again & again after water damage.

Water damage is the worst thing can happen to the phone. 

Turn it off immediately and and take it to the nearest Apple Store or an authorized service provider, maybe you'll get everything fixed.

If you have an Apple Care insurance coverage, try an Apple store. But if you don't, the only thing they can do is $$$$$$$$ ! Your iPhone will be changed.

Liquid damage to iPhone or iPod isn't covered by warranty - Apple Support

iPhone Service Pricing - Apple Support

If you prefer to see if you're lucky (as I was) wait  for your phone to be completely dry !!!!!!!!! Then try it ! Once, i've thrown my husband phone into the washing machine (it was into his jeans) ! After days, it was working perfectly fine.

Don't leave your device in direct sunlight for an extended period of time, overheating can damage the internals.

Well, in this case you may search for a third-party service provider. Or let your phone dry for at least couple of days and hope for the best.

I'm not sure about the towel, evaporation needs dry air. The towel will make a barrier to evaporation.

getting it dry is only ½ of the fix

the moist kills it, removing moist stop the slaughter but the parts already harmed will not be revived