1st thing I would check, which the other company may have done already I would hope.
Check the wiring connections where it connects to house wiring behind toe kick.
Seen many where connections fail causing unit to be dead.
These units pull more amperage than domestic units 11-12 amps when heating water. If the wiring connections are not tight they overheat and burn up.
- Samurai Appliance Repair Man likes this