Firstly, you have inherited a clunker. You'll get a few good replies here, but they are for sport only and you should well and truly rip it out and put in something from this decade. You also don't know what other codes exist within the alarm.
My guess: "int temp" may be a bit of bad handwriting and may refer to "internal tamper" (or variations on the theme).
The 'box' has a tamper switch on it, and your inability to close it would suggest the panel believes someone is tampering with the system. Not sure why you can't close the box anyway, but have a look for a little switch and manually depress it, seeing if the problem goes away after a further arm/disarm.
When you refer to pressing one of the "zones", I assume you mean pressing the keys on the keypad. Bear in mind that that system has "hold down" functions, for example you hold down the number one, it will test the external siren, hold down 2 to test the internal siren etc. That is probably the behavior you are seeing.