Tell me which openwrt assembly to choose for this router, there is practically no information on it on the network.
On YouTube there are versions for flashing and unlocking the web interface.
Proev next: after the firmware does not see the SIM card, change it.
When you roll back to the backup, the sim also does not see it, the sector may be damaged or ..
If it is not in the Table of Hardware then it is most likely not supported. If you could provide some more information about the vendor, some specs page in the internet, or a wikidevi link it would be helpful.
every device type have specific flash (disk) layout
on the flash, there is radio calibration data, which is again, specific for every device
if you try to flash some random image on router, there is a BIG chance that you will
a) brick device
b) destroy calibration data
so, without serial console, bootlog, and similar "hacking" no one could be sure what is proper DTS (device tree / hardware description) for your router