I haven't worked on key systems for many years, and am not familiar with the different KSUs(i.e.,Avaya Partner vs Norstar DS5)and the limitations of their PBX-like features (hybrids).
I was called on a repair for a "crashed" Norstar DS5. It had lost its programming due to a faulty card not keeping the programming when power was lost, and it reverted to factory fault. It also had all DIDs down, and all outgoing lines down in the line pool. I figured these out to be carrier problems. I was impressed that the Norstar handled DIDs. But when I went through the diagnostics and tested, I could not understand how to detect a defective DID card. A simple method would have been green-good/red-defective LEDs, but unfortunately all LEDs are red, and there are no LEDs on DID cards.
Sure-trial and error. roll them. Is there a better way to test for defective DID cards?

I meant to say "reverted to factory default".

Lousy typist! Details are hard enough to type with 2 FAT fingers.

Testing analog DID carts can be done with a "butt" set. Clip on to each trunk, go off hook and dial the send digits. You emulate the CO. You can also take each line out of service. The reason your DID's are not working is lost program. DID's must be programmed to target lines. Depending on your system size and DID range you have a lot of reprogramming to do! Put a BIG ups on the system until you can get the software/memory cart replaced. Be prepared to reprogram the system again!

Unfortunately, the carrier (I won't mention any names about bankrupt companies..) DIDN"T KNOW the send digits, and I had to guess which line the DIDs were pointed to. At least they were good enough to busy out the first line (dead), so the calls could come in after programming.
Also emulated the wink from the CO and there was no wink back from the system, which helped. But it seems like the Norstar diagnostics should have had a procedure revealing a disabled state. Even though I could test the module, it would only indicate whether I was ativating or disabling, when pressing "State". And, I had to test each slot and port, one at a time- didn't know right off which port the DID cards on the extension board were.
Also, there was no alarm on the set, nor any indication in the system log that it had lost power. I guess because it had DIDs I expected too much from the Norstar-like a "real" PBX.

Lucky it was a small system, and the receptionist remembered the extensions. I have the information now, for my return with the new card.

Thanks for the reply.