1) Check Battery Charger Board feedback at U123(U77) Pin 5 of CPU Board 2) Check Battery Charger Board feedback and make sure it is going out to the CPU (TP-6 on the Battery Charger Board) 3) Check the ribbon cable from the Battery Charger Board to the CPU Board 4) Batteries may be defective If Voltage Is Really Less than 90 volts 5) Bad Battery Charger Board 6) Loose Battery terminals. 7) Check for possible bad LVLE Power Supply 8) Check for possible bad 1kHz board 9) If Rotor Controller Board oveheat, circuit breaker tripped tooor same time