Car alarm won't reset after disconnecting car battery

Try disconnecting the battery and leaving it overnight. Unlock the car, insert the ignition key and switch on - then reconnect the battery.

That sometimes works. If it doesn't you will need some experienced advice and specialist help. Rover/MG usually needed to be opened by whatever locked the car to avoid the alarm sounding. If the key was used to lock it, then using the key to unlock should be ok though I seem to remember the alarm will sound after a short time if the key isn't put into the ignition and switched on fairly quickly.

O.K. Jeanne lets start here did you disconnect the battery or did it go dead yes/no if yes when cables were reconnected ///or battery jumped the alarm went off putting the car into theft mode and that's why the no start condition flashing red alarm light=== you have to disconnect the battery again and when you reconnect it the alarm will sound when it does you have to press the remote control button///key fob to stop the alarm and you will be able to start the car please post back if there's something else and please the most important thing to remember is that any one here who wants to help you is not standing there with you so everything must be told be very specific about what's happened ///happening O.K.

This is a wild guess, but disconnect the positive terminal from your battery. Touch the cable (that went to the positive) to the negative, to drain out any capacitor in the system that is holding charge. I think you have to short it that way for about 10 seconds. Reconnect cable to positive and start car.

That will reset your computer and should reset the alarm as well.

I just had the same prblem. Reconnect your alarm first of all. You need to use your key bob "remote" to deactivate the alarm before starting. It is a feature "good one" i might add that should someone try to steal it the jeep will not start until u deactivate it w theke bob.

The alarm system somehow got activated , this is usually because the battery becomes discharged or disconnected try doing this:
Remove the key from the ignition
disconnect the negative battery terminal
put the key back in and turn to ON
exit the truck and leave door open
reconnect the battery terminal
get in and leave door open, if the alarm horn stays off it should start.

First of all disconnect the battery, wait 5-10 minutes, then reconnect it to reset the alarm system. If this doesn't work you have to take it to dealership, could be a faulty alarm ecu.

hand it over to a mechanic or Nissan. If you recently had an M.O.T and it went of quickly then ask for a refund, even better, ask him to take a look at the car again

Disconnect the negative battery cable for five minutes, reconnect and see if the system resets.

After reconnecting the battery press the FOB 5 times that should reset the alar.

Sounds like you have an aftermarket alarm with starter disable. By disconnecting the battery the alarm reset and the defualt setting is usually to set the alarm automatically (active arming). You have three options..
A. If you have the key fob that went with the alarm you can disarm the alarm.
B. If no key fob is available you can disconnect the battery again, turn the ignition key to the on position and reconnect the battery. This usually doesn't allow the alarm to set and allows the car to start.
C. Remove the aftermarket alarm system. This is usually the long term fix i recommend if the fob isn't available. Option B should get you going though.