AMG GT Hybrid Alarm System Electrical Issue

I had a similar problem with my AMG GT. It might be the auxiliary battery. Have you checked the battery? A system diagnosis should help pinpoint the issue.

Is a battery check done with a multimeter? Where is the auxiliary battery located, and is it easy to get to?

A system diagnosis is better than a multimeter for assessing battery health. I recommend a workshop. They can inspect the auxiliary battery and connections, as it could be related to normal wear.

Thanks. I took it to a shop, and it was the auxiliary battery. The replacement was 330€, and the alarm system is now working correctly.