Sorry but I wasn’t available yesterday. If you don’t have experience with opening electrical panels and electrical water heater heating element wiring, don’t do it, call you electrician.
Did you check the electrical panel to make sure that the red and black wires you’ve connected to the water heater are actually secured to the terminals of a 220V circuit breaker? Maybe somebody used a white (the one you capped) instead of a black or red?
If colors are matching on both ends; using an electrical voltage tester check both terminals on the breaker to make sure that they have power (breaker must be in “ON” position) and at the WH’s wiring box end.
Applying power to the appliance or lack of water inside the tank might have tripped the heating elements reset buttons. They are hidden under the access plate(s) (one or two depending on the design / size of your appliance) for the heating elements, located on the side wall (top and bottom area) of the water heater. You may need to reset them.
Let me know if this helped or if you have more questions, just click “comment” below.