Hi there,
Do you think there is a possibility you could have reversed the jumper cables for an instant when you jumped the car? If you did, it's quite possible you shorted out some diodes in the alternator. They would cause the battery to discharge very quickly. Try feeling the alternator after the engine has been off for an hour or so to see if it feels warm. If it is, that's your problem. There are other parts that can be easily destroyed by careless "jumping", but the alternator is the most obvious and will drain the battery quickly.
Good luck,
Richard Wooldridge
'82 300D/4.3LV6