Last night my alarm kept going on but no sound only flashers going off ? Last week I had 2 new horns fitted and no problems all week. Went for a run opened all doors windows bonnet and still went off so I sat in the car and locked it 5 minutes later flashers going off no alarm I decided to switch of the inside lights and pressed my garage door opener red plastic bit and locked the car and went in no more problems. What is happening ?