Either the battery has been damaged by an incorrect jump start or the car is suffering from parasitic battery drain caused by a circuit that continues to draw a charge long after the car has been switched off.

If the car is suffering from parasitic battery drain then it could be any one of a number of things (boot light, radio, interior light etc). Best to have a parasitic leak check carried out by a garage to identify the cause. You can do some basic checks yourself by switching off everything and seeing if the battery holds a charge. You can then switch each circuit day-by-day until you identify the faulty unit. If this doesn't solve the problem then I would suggest seeking a reputable auto electrician.