Firstly ,Nordic use webasword generated in unknown ( by me ) way.(Not only Nordic , but lot others).
So loading it will couse , that you will be not able to login to web . Nordic routers have their uniques passwords on labels under router.
With Elisa is simplier ,since web password is the same as wifi password ( and wifi password is easy to recover).
TIM use standard password "admin".
And secondly , i was not able to find a Firmware files . I tried to copy flash memory from Nordic , and that works , but web password changed , and also donors password not worked.