Nighthawk MR2100 will not boot LED is blinking red

Hello dear community,

I already have the third MR2100 in which, after switching on, the screen remains in the boot screen and the
red LED flashes. I can access the device via a LAN cable, but only as far as the first page and it doesn't go any further here
either. I was able to find out on the net that it is a firmware error, but I can't find the firmware for the device on the net
and I don't know how to install it either. Unfortunately, the warranty for this device seems to have expired.
Do you have an idea where I can get the firmware and how I can upload it? Firmware version should be NTGX24_10.17.08.00. Thanks so much!