Hi, I have been using a 12/3000 flawlessly for 2 years. Last year cleaned connections and replaced lugs with proper crimps and added lithium. I have a line filter that monitors surge, Hz and power characteristics. Everything still worked fine and my batteries are fully charged at 13.4V.
Today, I plugged in AC source (generator and shore) and no AC gets passed through and the batteries do not charge (however the inverter works fine). I measured 120VAC at the first input terminal (on the left). When I connect AC source, the 12/3000 beeps and clicks then beeps and clicks again 30 seconds later. After 4 or 5 beeps and clicks, it stops trying.