Question about ASUS ZenBook Pro Duo OLED

A few days after the warranty expired, the battery broke. We couldn't find a way to replace the battery. Since then (3-4 years) we have only been using the laptop with a power cable. It's a real shame for this brand, but it just happened.

I've been using it plugged most of the time and didn't really pay attention in the beginning. But after these years now it's rightly 1.5 hours with everything running, videos, music etc