The device is not connected can point to one of the following situations while attempting to rebuild the tombstones:
Not all drives in the storage pool are connected at the time of installation (did you use external disks in the storage pool?).
Not all drives in the storage pool are detected. This can happen either due to missing drivers or due to a faulty disk.
Also the Windows Home Server DVD should remain in the DVD ROM drive all the time during the installation process.
If you cannot fix the situation, you should try other recovery methods as described in the FAQ
How to recover data after server failure.
Best greetings from Germany
Olaf