A 0.6A (600mA) drain is far too much.
You should be getting around 0.05A (50mA) on a standard car and still under 0.1A (100mA) with a few extra alarms etc.
With the meter on and the bonnet switch depressed, pull the fuses one by one to find out which circuit the drain is on.
If you need to check the fuses inside the car, open the driver's door and then manually push the catch over in the door. Now lock the car again and you can check the inside fuses.
If none of the fuses reduce the drain, disconnect the large terminals one by one as I've seen the alternator cause a drain before.
Work methodically and you should be able to trace the drain.