AudioMoth fails to write on microSD card

Hi all,

Last autumn I have received my first AudioMoth and aimed at trying it out for the first time just now. I have downloaded all Apps, set the time and flashed the device. I have then inserted batteries and a microSD card, and tried to record according to my set schedule. However the AudioMoth started blinking in a way that indicates that either the writing proccess failed or it was at low battery (the latter being not likely as they were new).

I have tried both in custom, and default modus. Same result. I have tried out different batteries, and microSD cards (both exFAT and FAT32), without success. The microSD card is appropriately snugged, too.

I am wondering what I am doing wrong, or what else I could do to make the Moth work?

Thanks in advance and all the best,

Diandra