One thing to make sure of is the tank being completely full of water. If the hot water connection is at the top your good to go. If its on the side of the tank, you will want to burp the relief valve, by lifting the handle a bit till only water comes out.
Then with a multi meter check for ohms across the two heating
element terminals (with the power off of course). Any reading means its good, An open means the element is shot.
Can also do same continuity check on the high limit and thermostat. With a cold tank both should be closed with unity on the meter. an open reading indicates a bad item.
When replacing a heating
element, make sure the relief valve is open (via handle) while refilling the tank. Its very easy for an element to burn out without water around the element. Happens alot in residential replacements
Also with a side outlet tank, you'll want to burp the relief valve after you run a water tank out of water. Otherwise air can be trapped in the water heater. Not a big problem on land, but can be on boats.