S40 V40: Cannot stop alarm going off!!

[Andru]

After nights last night my son did something to my'99 volvo s40 where now the alarm goes off all the time.We do not use the key fob to lock the car ever just the key he did something this morning to set off the alarm when he needed to jump start his scooter so he opened the bonnet.The alarm started to go off and the only way i could turn it off was to disconnect the battery.When i got up this afternoon i recoonected the battery but noticed the hazzards were flashing and then a few sec later the alarm went off the key fob would not turn it off so i did the battery again.Now as soon as i connect the battery the hazzards come on and then the alarm.The only way to stop it is the battery to be disconnected.I have tried new batteries in the fob but that does not work.
I'm stuck now and need the car for work.How can i reset the alarm or disconnect it alltogether so i can use it.

thanks

[4 forty]

check the micro switch on the bonnet catch sensor,these can stick in the open position due to dirt.

[Andru]

I've looked around for that where abouts is it?

[4 forty]

its actually part of the bonnet catch, you will see a very fine steel strip coming from the micro switch

[Andru]

thanks

i'll have a look

[Andru]

I finally found out what he did.
he open the car with the fob then closed it with the fob,activating the alarm.I just opened the fob and found it had a cr2032 battery in it, instead of 2 x 2016 batteries.Hopefully when the wife gets home with 2 of these from the shop i will be able to sort it out.We never use the fob because it has never been reliable,i can see why now.

I'll let you know tomorrow morning if it is all ok,another 12hrs in work again!!!

Cheers for the suggestions.