Inverter cooling pump dead.[br]
Your coolant level will be steady, but what you really need to check it's if coolant actually flow [br]
Can be checked inside small semitransparent expansion tank close to the inverter.[br]
More reliable way - OBDII scanner, if you see code P0A93 almost 100% pump is dead.[br]
If you wait for inverter to cool down you can safely drive to home (not far, not fast).[br]
But keep in mind - inverter more expansive than pump :)[br]
So... pump: 25$ aftermarket (good for 1-2 year), 70$ original. Plenty of YouTube how-to.