I am not familiar with the test meter you said you were using but make sure it is set on
ACV . With the breaker on touch the meter leads to the two screws on the end of the top element that has the wires under them . You should have 220/240 volts reading on your meter . If you do & the heater isn't heating the element is bad . If you don't have voltage there try the same thing on the bottom element . If no voltage at either element you have a bad thermostat , bad connection where the wire from the panel connects to the heater wires at the top of the heater or no voltage coming from the breaker . Another way to test the elements is to turn off the breaker , loosen the screws on the end of the element , remove the wires from under the screws & take an ohm reading on the element screws with the wires removed . You should get a good ohm reading through the element . If you don't the element is bad . After doing this you should also touch 1 meter lead to one of the element screws & the other meter lead to the metal tank . Repeat using the other screw & tank . You should not get an ohm reading between either screw & the tank . You can't get a correct ohm reading through the elements with the wires attached . In my experience 90 % of the time when a heater quits heating the top element is bad although of course there's always that 10 % .