Have you checked the breaker? My breaker sits next to the 100amp relay, and its located between the solenoid & compressor (just in front of my starter batteries).
Couple months back I thought my Extreme Air seized (I had been through high water couple months prior to that). Contacted manufacturer and we concluded it was either the 100amp Relay or the air pressure 145psi switch...so I replaced both - Wasn't either. Turned out when I had the new Maher starter installed they failed to reattach the cable.