I have left the key in the ignition and now have a flat battery. Could you please advise me about where the points are to fix the jumper leads and if I should be aware of any problems I could cause. Thank you

no
batteries have just the 2 posts
1 is positive and 1 is negative
connect one lead onto the positive post of the jumper car to the flat battery positive post
then connect the other lead to the negative post of the jumper battery of the jumper car then connect that lead end to the engine ( any bolt will do) do not connect to the flat battery negative post

Have you replaced the spark plugs and checked the leads,have you got enough fuel?

probably is the alarm being set off by a corrupted CPU program from connecting the leads incorrectly. When using jumper leads or jumper battery the positive lead is connected to the battery terminal first and the earth wire ( negative) is connected to the to the engine . NOT the battery. IT is also advisable to turn on the head lights These precautions prevent a power surge in the CPU that corrupts the program

Disconnect the battery terminals and jumper the positive and negative leads together. This will completely drain the computer and it will have to reset itself as it comes up. Leave the jumper on the leads for an hour or so. When you reconnect the battery, your problem might fix itself.

Remove battery, clamp both battery leads together for 5 minutes.
reconnect battery (positive first) gives vehicle computer hard reset.

Then perform key reset as factory handbook.

Hi Duncan, I would advise against disconnecting the battery as it may give a problem with the key coding. Use jumper cables to another vehicle. Once connected start the other vehicle and then switch on the lights of both vehicles together with the rear screen defrost, (this will stop any surge when disconnecting, and alleviate problems which may occur to the electronic managements systems.) Start the Benz and then disconnect the jumper cables from both batteries being extra careful to keep the crock clips apart. Take the vehicle to a battery shop and have the battery checked. Regards Johngee10

Try starting in Neutral instead of Park. If this works, the transmission range switch (sometimes called a neutral safety switch) is faulty in Park.

Next, you can try a remote start switch (available at auto parts stores) or a jumper wire to bypass the ignition switch. First make sure transmission is in park or neutral. You will be jumping from the battery positive terminal to the starter solenoid. The starter solenoid terminal has a black wire with a white stripe connected to it. (This terminal is visible just to the left of the automatic transmission dipstick tube.) Remove this wire and connect one end of the remote start switch wire (or jumper wire) to it. Connect the other end of the remote start switch wire to the battery positive terminal. Activate the remote start switch and see if the starter will crank. (If using a jumper wire, briefly touch the other end to the battery positive terminal and see if cranking will occur). If the starter works then you have a problem in the ignition switch, or starter cut-out relay.

The starter cut-out relay is located on the back of the driver's under dash fuse/relay box in the left wall kick panel. The ignition switch also has wire leads that plug into the back of this same fuse box. You can disconnect the wire leads and test the ignition switch with on ohm meter from this point.

There should be a red "+" point under the hood. Connect jumper leads or a booster pack to this point and a good earth point on the chassis or engine block and use the remote key fob to open the trunk.

Is your leads of good quality?My advise is to charge your battery.

e36 m3 cab flat battery.i have now fitted a new 1 and my alarm will not work and the car is immobilised.the key fob is black with 1 button in the centre and the car is a 1995 can you help.