|"I have even tested the RAM on two other systems and it worked just fine."|
You MUST unplug the AC adapter and the main battery whenever you unplug or plug in the ram, because it's ATX mboard is always powered in some places, including some of the contacts in the ram slots, even when computer is not running, as long as the main battery is installed.
Did you do that at ALL times ?
If you didn't, it's quite possible for the ram module(s) and/or the ram slot circuits to be damaged.
Ram working fine in other computers proves there's nothing wrong with it, but it does NOT necessarily prove it should work in your mboard.
Not all ram that you would think should work will work in your mboard. The ram has to be compatible with you using it in the Tecra A9 series.
A look on the web finds this series is specified to support max 667mhz ram - PC5300 - but that's not the only thing that determines whether it's compatible with using it in your mboard.
If you are trying to use an 800mhz module - PC6400 - the PC6400 spec itself is backwards compatible with the PC5300 spec and your mboard would run it at 667mhz, but that's not the only thing that determines whether it's compatible with using it in your mboard.
A few ram manufacturers may list specific 800mhz ram that works in your model - e.g. Crucial does - but most list only specific 667mhz modules.
See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
Correction to that:
Once you know which module ID strings (part numbers) work in your mboard, you can get them from anywhere you like that has ram with those ID strings.
If you have brand name ram, it is usually easy to look up whether it's ID string is in a list of compatible modules found by using your mboard or brand name system model number.
If the ram is generic, that may be difficult or impossible.
It is easy to test for incompatible ram that has caused your mboard to fail to boot.
Unplug the AC adapter and the main battery. Remove all the ram.
Install at least the main battery, and optionally connect the the AC adapter.
Try to boot.
If nothing else is wrong, you will get no video but you will hear a pattern of beeps that indicate no ram is installed, or a ram problem.
E.g. for an Award bios or a bios based on one, that's often a beep of about a half second, silence for a half second, a beep of about a half second, silence for a half second, continuously.