Sounds like the main controls battery may need replacing.
Hi, as you know your system is old. The company that made your system no longer exists. There is no support for your system. No parts available. It sounds like a circuit board problem. Defects in circuit boards are not normally fixed where I work. Not cost effective to pull panel and send it out to be bench tested. shipped back for reinstallation. cheaper to replace panel and keypads. There is a 50/50 chance you may have to replace sensors Too, on that panel. Hope this helps.
Hot is ok in an alarm box, especially inside where you see your finned heatsink and capacitors, if it beeps it might be because you have a communication problem, a weak backup battery or else. Check if you have any codes being displayed on your LCD or LED and check in the signification in your user manual if any. If you are connected to an alarm central they should be able to tell you what is the problem by connecting remotelly to your system. If not, well I need more details.!