Nighthawk M2 (MR2100) wont tunr on

Hello
I have been having a problem with my Nighthawk M2 Mobile Router (MR2100 100EUS) for a few months now.
Last year it started that the LCD screen including bottuns were not responding, but when connected to power the modem turned on and my devices connected automatically. So that was fine for me.

Now since 2 months, the display only shows the white start screen "Netgear with the 4 dots" and nothing more, for hours until the battery is empty.... I can only remove the battery to switch it off; pressing the buttons still wont work and also pressing the reset button (once or for longer) does not cause the router to react at all.

Is there anything else I can do?

thanks in adbvance and

kind regards