Take the outside cover off the WH and make sure the drain plug/anode has been installed and the pressure relief valve shut. Then you'll have to look for the WH bypass valve(s) and make sure they are set for normal use. You might have just one valve and a couple of check valves, or a 3 valve system like the one pictured.
In this photo, all 3 valves are in the open position, which isn't what you need for normal use. The center by-pass valve should be set with the handle 'across' the hose in the off position. Winterize position would be the upper and lower valves shut, the center valve open.