No internet connection

I made a new contract for Fritz!Box 6660 Cable to be activated on 04.03.2026.  Even though I got an email that the activation was successful, after the setup, nothing seems to work (no internet connection). The ‘power on’ light keeps blinking without end. 

 Please help as quickly as possible. Thanks

edit o2_Manga: verschoben von Internet: Router…. zu Englisch: Broadband & Landline