Bonnet open indications , sets off alarm how do I disable alarm

See if your dome lights work when opening the door. Usually a door latch.

There is a simple solution; you just have to bypass the hood switch, which prevents the alarm from arming as it thinks that the hood is open.
To find the switch, pop open the hood and look at the cross-member on the right of the radiator. Connect the wire to the ground to bypass.
Now you can safely unlock the doors without the alarm going off.

On my 94 Sovereign there is a switch inside the centre console that will switch off the alarm, not sure about the 96. You could try locking all the doors. connect the jump leads and then unlock the doors (the bonnet switch for the alarm I think is the same one for the under bonnet light so you might have to tape it down whilst the bonnet is open, just to confuse the alarm )

Good luck

Plug your ears first, open the car with key, open the bonnet to get to the battery, disconnect one battery terminal and cover this with rag to avoid a short circuit. That should reset everything - alarm, radio. Do not lock the car. After an hour reconnect the battery. Hopefully alarm will have reset and then use the key in the ignition. Hopefully starts but you should buy a replacement button for your car and security system. If alarm sound again, disconnect battery again and call an auto electrician.

Sounds like the bonnet switch might be going out. You have an electrical contact switch that tells the alarm computer if the bonnet is open or closed. Either a miss adjusted or worn switch will send a false signal to the computer making it think it is open when it is not, you will also want to check the wiring that goes to the switch for signs of chaffing or kinks as the wire itself could get and send a false signal.

check the hood switch, sounds like its saying to the security system that the hood or bonnet is open.if its a x350 model the switch is on one of the bonnet latches,

Alarm circuitry usually memorises the battery voltage half a minute-ish after being set. If the sensed battery voltage falls too fast because the battery is (almost) faulty or in a low state of charge, the alarm brain will believe a door has been opened and switched on the interior light.
That is one scenario of several possibles...

Shaking the car is very unlikely to trigger a modern car alarm though opening a door should - because it doesn't it might indicate it isn't being armed (or fully armed), perhaps because it can't find a stable battery voltage to lock onto or perhaps it thinks there is a door, bonnet or boot open due to defective switching, the bonnet is most likely.

the alarm is the fault refer to your alarm manual to disable it, if you don't know about this unit it is best to seek help from someone qualified and available to look at it for you, it seems as if your alarm is set, most alarms have a starter disable function and the alarm going off is an indication that it is set.

try bypassing the bonnet switch, my switch was no good would set off the alarm because it use to think that the bonnet was open

I HAD THIS PROBLEM ON MINE,TRY CLOSING THE BONNET FIRMLY (SLAM IT SHUT) TO SET THE BONNET SENSOR SWITCH PROPERLY.