From the Sonos LED Support page…

Flashing red battery LED

The portable Sonos product is experiencing a fault condition. If you see a flashing red battery light, contact Sonos Support.

My guess would be the laptop charger doesn’t have enough voltage or amperage to charge it properly, but Sonos support could be much more definitive.

Thank for your Feedback. It only flashes briefly in the beginning after it stays red.

This taken from a much earlier post in the community…

The power adapter must be USB PD (Power Delivery) certified. For 45W operation the PD source must output a power of either 20V/2.25A (or higher current) or 15V/3A (or higher current). For 36W operation the PD source must put out 12V/3A or 15V/2.4A. Charging speed is reduced if listening to audio at the same time. Anything less than 36W will not power, or charge Move.

I occasionally use this charger (see below link) when travelling, as it will charge up-to two Moves at the same time and it can charge the Sonos Roam speakers aswell…

https://www.amazon.co.uk/gp/product/B08CVFMGL1

Ok but my charger offers 20 V with 3 Ampere. But it seems then that Move does not comply with the charger... I was hopeing that the light could indicate some Information or handle some more energy Inputs - especially since the device is not very cheap...

I don’t think your charger is designed to correctly charge the Move - it does not appear to be PD certified to handle the power output (volts x amps (wattage)) mentioned, so I’m a little concerned that a spike in power may have perhaps damaged your device, but see what Sonos Support Staff say when you call them. I hope that you can get it back up and running and if so, then maybe set that particular charger aside, going forward, just in case it is incompatible.

Thanks Ken