Power Supply/Inverter Comms. Errors

I am working on an Optima XE 90 that is giving me a list of errors: D103 - Inverter Communications: Inverter I²C error D104 - Inverter Communications: Inverter ADC I²C error - U21 D105 - Inverter Communications: Inverter I²C I/0 Expander error D107 - Inverter Communications: TEM ADC I²C error - U24 D205 - Power Supply: Inverter +18V supply too low (5.5VDC) D209 - Power Supply: Inverter -5V supply too low (