Congratulations and welcome.
I don't have the tankless water heater but can provide some recommendations I've "heard" about them from the forums here:
- Is it on?--simple question "is it plugged in"
- Are you getting enough water flow/pressure (the consensus is that they need enough flow through them to detect that and turn on)
- Once on you adjust the hot water flow rate to get the temp you want--not by mixing in cold water
Thats about all I got...