I think there is an internal flaw in the alarm system. Sometimes the alarm goes off and sometimes it doesn't. Other seems to be completely random. What could i be doing wrong?

Based on all the info you have provided I think you need a professional to get involved here, I am not willing to "GUESS" what might be the issue or issues (more likely more than one).
Good luck

Hello,
Check the battery in the vehicle and the battery in the actual keyfob itself. Sometimes when one of these are low the alarm will randomly sound. The random alarm sounding is typically an indicator of a low battery somewhere. What is the year make and model of the vehicle? Some, like bmw's, have sensors under the hood, on doors and windows that get stuck and randomly sound the alarm. Please Advise

replace the internal battery in the alarm system or complete alarm unit. the random alarm is its way of telling you the battery is on its way out

We do not have info on aftermarket systems. Suggest you remove it completely and install a quality system.

Sometime a weak battery or a battery that is going weak will do this. What happens is as the car is dormat the small voltage used to keep ECU alive drops and triggers a voltage drop to alarm( like it should for unauthorized entry).

Over a period of time most cars will drain battery. Clocks ,alarms and other bells and whistles that the new car have all need power.

well if it only seems to do it when u go into places where u can not hear ur alarm when it sounds then more than likely its telling u that the alarm had been tripped. Most alarm systems have that feature that it just chirps every so many secs to let u know.

try parking in the shade. if that doesnt change it then it is your tamper sensor, i understand that you think there is no movement, but that doesnt mean that electrically there arent slight variations in power. try to lower its sensitivity if the shade thing doesnt work out.

there is a hood switch located at front passenger side under hood. check to make sure the plunger at hood is pushing the switch completely down. sometimes there may be just enough clearance that a strong wind will set the alarm off.

how to turn the alarm system off