I've had 2 fail in the last two weeks.
Two different customers have had the same thing happen.
Advanced monitoring says the card is working.
Little check mark.
The card itself seems to reboot with it's watchdog over and over. The card flashes once, tries to load and then after a few seconds this starts over.
On the second system, it was 5.1, upgraded it to 6.1 and that didn't help. Replaced the card, and the replacement card immediately starts working.
Each was about 5 years old.
I'm used to rarely having the problem actually be the card as opposed to telco.

Did you test the circuit before replacing the module? I had a similar issue with an EL and a PRI. Windstream insisted the circuit was working. When I replaced the module, the circuit started to work, but then, after a week or two, would fail again. The last time it happened, I jacked in the T-Berd into the smart jack and the circuit started to work. What I saw was the circuit going in and out of sync, sometimes 10 times in a row. Of course, with the T-Berd in the circuit, the Mitel saw a good sync in the circuit.

The only way I could get the Windstream tech to fix their circuit was to have him come and see for himself. He mumbled something, went back to the CO. The circuit went down for a couple of minutes and then came back up. It has been working without error for a year now.

Rcaman

I did not.
I wasn't involved with the 1st one that was replaced at a site about 2 weeks ago.
The second site, I just brought out a replacement card to the tech who had gone to site.
The only real testing done was with a loopback tester.
Failed to get a reaction from the card, looping to the smart jack made the smart jack happy.
But, with your example, the thing is I think these 2 are the 1st I've needed to replace.

I've only had to replace one, and it behaved exactly as you describe. Sounds like a coincidence that you had two fail in such a short period.