Hi! System damaged by storm. One of the 2 trunk cards was keeping the system down. Replaced both trunk cards and system came up but was randomly restarting. Replaced the base unit but used the same already replaced and bought new trunk cards and the same 7.1 software card and it worked fine for about 2.5 weeks. Last week it restated once and yesterday a couple of times. Installed Tower MAX SurgeGate MCO8110 for the trunk lines and a UPS for the system and voicemail but it restarted several times after that. The telephone company supposedly checked the lines after the storm. Any ideas?

You have replaced it all except the software.
You can:

..1) Default (erase) software and re-program from scratch or restore if you have a backup and only if backup is PRE-Storm and after defaulting memory.
if that does not work then replace the software.

..2) Replace the software.

Changed software to 7.1 and erased memory twice; we'll see what happens!