I replaced the battery on my 2005 BMW 525i and now it wont start the starter doesnt make i tried jump starting it but it didnt start

Disconnect the battery, have the ignition key turned to the "on" position then reconnect the battery.

Sounds like your key switch is malfunctioning.

Certainly sounds like a lack of power in the battery.
Do you have a genuine BMW battery or a cheapie replacement?
Have you tried to jump start the vehicle.
Batteries can seem ok, but when called upon, the power drawn out of them can be insufficient.
Try charging battery and starting on the charger- or just jump start to see what happens

rarely fail,but do.if the battery load tested out to be good . you get 12 volts to the starter signal wire when you turn the key to start. then the starter is bad or the engine or something driven by the belt is locked up.

Does it crank and not fire , if no crank check battery jump start , if no fire check for spark fuel and injection

hello there
eventhough you are in Porsche forum i think you have a problem with your starter i would replace it
proiporsche

Check also your connection on starter

Check the battery +12v power connection to the starter is in good order,
Check the ground connection between the battery negative and the engine/starter motor is robust and intact.
If no problem with above, replace the starter motor.

THE BATTERY IS LOCATED IN THE RIGHT SIDE OF THE TRUNK IN A COMPARTMENT .... COULD BE THE BATTERY IS DEAD AND NEEDS TO BE REPLACED.... JUMP STARTING YOUR CAR CAN LEAD IN SERIOUS ELECTRICAL PROBLEMS .... YOUR BEST BET IS TO GO TO YOUR LOCAL BMW DEALER AND PURCHASE A NEW BATTERY

new altenator,sounds like you put the cables on the wrong way round

could be 3 things being i cant see it...either the starter. alternator...and doubt it but could be water pump