after turning off the car, it won't start again, charged battery-no effect

Let Contra Costa Auto Service in Concord look at it. They work on a lot of European vehicles and would want to start with a charging system test. Call (925)798-1205 for an appointment. GL

You need to determine if your battery is dead or not 1st. Does anything turn on? Does the horn honk? Does the engine crank over, but doesn't start? If the battery is good, then you have either a alarm issue, Clutch switch(make sure your floor mat isn't jammed under your clutch pedal) starter etc...