You will really need to get directly into the alarm control box. Not the alarm sounder under the bonnet or wherever they have fitted it but the main box somewhere under the dash, in the footwell, that sort of area. You will find a box with a fairly large 3/4" or so loom of cables going straight into it with no connectors. To bypass mine I had to pull the alarm unit out completely which involved drilling out the pop rivets and pulling the connector inside. I then had 6 black wires which untraced to two relays in the alarm. One pair cuts the fuel the other two pairs cut the starter and both had to be bridged.
The other method is to gently take the front off the dash and find where in the loom they have connected the starter and fuel solenoid interrupt wires but you will still have an active alarm.
If I were you I would lift the sill trim that attaches to the footwell side piece under the dash and locate the alarm box wherever it may be. The best method is to get air moving around it or blow out with compressed air, even from an aerosol of compressed air. A vacuum cleaner with the hose attached to the outlet of it to blow like some of the older cylinder cleaners do will give warm/hot high flow air that can be directed. This can help but compressed air is best to get the worst out. You can try WD40 which is water repellent, that may work especially as you can fit the straw to it and get it well inside the alarm box.
The alternative is rip the whole thing out and find the wires that get bridged by the relays but this is an hours work with theorist tools and meters.
It's made to be tricky for a reason.
I'm not sure the bonnet or door switches will be your problem as your alarm stays set and quiet but just won't unset on the fob.
