My base says fallen, team members have helped but I can’t teleport and status is still fallen. What..

You can spend resources to remove fallen status, or you can wait 24 hours and it comes off automatically, or you can be zeroed by another alliance and ported away from that area (but you'll still be fallen).

When fallen, you can only build on your own tiles - this is why you should always have a safe port ready, just in case.

I the latest Eden, there is an option to port yourself back to your start point, doing this will take your tiles and resources. But it's an option to escape if you are being zeroed over and over at your current location.