Why is there still no hot water after installing new thermostats and elements?
After being sure the water tank is full of water (which would not be the case after replacing an element) and the cutoff valve(s) are on, be sure the power is on.  If you see voltage at the elements, it has got to be heating water.  Unless they were not wired correctly.

If you had just turned it back on, give it 10&ndash;20 minutes to detectably heat the water.

A photo of the final wiring arrangement along with make/model information and observed voltages would be very helpful.