We just got bought a BRAND NEW water heater and apparently we didn't install it properly and burned out the elements, but we've replaced the elements and it doesn't want to heat up the water still. What could still be damaged?

What did you do wrong during the installation that caused the elements to burn out? Wired it wrong or forget to turn the water on before turning on the power?

Thermostats.

Well I actually forgot to let the air out first, which in turn burnt the elements, but I've replaced the elements and its still the same. Could it be the thermostat?

I just don't want to spend more money on something that I won't need and can't return... I don't have much to spend and I've already spent too much money on buying the damn thing. So I'm trying to figure out what could surely be wrong before I go buying another part

How can you check if the thermostats are damaged?

How can you check if the thermostats are damaged?

Make sure the unit is filled. Turn on the power and measure voltage across the elements. Top element heats first and then thermostat switches to bottom. Should measure 240 VAC across top terminals of element and then later 240 across the bottom. Make sure breaker-should be a double pole-is turned on.

When the elements burned-out did it trip the breaker? Did you push the red reset button on the thermostat? What have you done so far? Do you have a AC voltmeter? This is an electrical problem. Start checking from the breaker's through the thermostats. Let us know what you find. Good luck, Tom

I don't own an AC voltmeter is there any other way to check if the thermostat is broken, and no the breaker didn't trip, and I've only switched out the elements pretty much.

Make sure you're comfortable, and confident about using a volt meter before you begin measuring voltage anywhere.
You can get a 240 volt reading at the upper element terminals, and still have a bad element. I prefer to test the upper ( or lower ) element by disconnecting ( safely ) the wire from one of the element terminals, and then checking for voltage at that terminal, and to ground; you will register 120 volts through the element as long as it is good, and, there is voltage leading there through the t-stat.

Either way if the elements aren't burnt again then it must be the thermostat, no? Because I have absolutely no idea how to use an AC voltmeter, and don't want to mess with the water heater wiring unless I ABSOLUTELY have to.

FYI though the reason i burnt the elements was because i didnt air it out enough.

Did you push the red reset button located on the upper thermostat ? Tom

Yes I did that after I installed the new elements and filled it with water, i pressed it

If the breaker is okay then the next thing I would be replacing would be the thermostat. Replace wire for wire and let us know if that works for you. Good luck, Tom

This may or may not help.
https://www.askmehelpdesk.com/attachments/electrical-lighting/43870d1372944066-troubleshooting-us-craftmaster-water-heaters-checking-water-heater-thermostat.jpg

You should also note that the red reset button is a thermal over temperature switch. It is not an electrical circuit breaker.