Dewalt DW9074 batteries go flat too quickly - Dewalt DW056 18 Volt Cordless Impact Driver - 1/4" Drive Hex Shank (Battery Charger and Case Not Included) - Tool Only

The battery is likely to be fine, but what about the electric motor in the saw, in rice as well? The only thing that tends to get damaged is electronic board components.

Rice only works well if it was warmed first, silica gel packs are better. A couple of days should be good, but my advice it open it up straight away and dry with a hairdryer or heat gun.

faulty or dirty connections

Here is the manual for the charger - note on page 2 the meaning of the problem you describe - time to replace batteries (depends how old they are)
http://download.sears.com/own/00925737e.pdf

That being said, check the videos out, perhaps can get it to work after all for a while longer.

The charger for the dewalt 18V battery.
http://www.ezbuybatteries.com/dewalt-72v-18v-battery-charger-universal-replacement-13821.html

A fully working 18v Dewalt Battery will only take 90 minutes to just over an hour to fully charge from going flat. This fully charged battery should last about 4 hours of use (depending on the load). So the answer is 1 hour.

Here are the codes for Dewalt Charger Flash indications:
---- ---- ---- ---- ---- ---- ---- Charging
------------------------------------ Charged
----- - ----- - ----- - ----- - ----- Hot/Cold Pack delay
- - - - - - - - - - - - - - - - - - - Replace pack

Remove the REVERSE-THREAD screw at the bottom of the chuck. Set the clutch collar to the highest setting, and set the gear to the slowest setting. Remove the battery! Get the biggest allen wrench you can fit in the end of the chuck(the shortest leg) and tighten the chuck down around it, allowing the jaws to rest and tighten on the flats of the wrench. Lay the drill on its side(chuck toward you, handle to the left, and allen wrench to the left, horizontal to the deck. Then with a hammer(soft hammer if you care about the allen wrench) quickly and deliberately hit the allen wrench in an attempt to cause the allen wrench to spin counter clockwise. Let me know if this works for you, and if not, explain what is happening.

Flat batteries?

did you consider the freq. hertz in your country & US.
50 to 60hz

Have you changed the AA Batteries, this is often the fault, when they are flat they lock the radio out. HHM Dewalt Service