Hi Ivan,
I assume all the APs are set to DHCP, please take a backup of both configuration and cluster backup, then please run AP CLI script on SZ100 to let all the APs know the new SZ100 IP address ( this is an extra step to make sure that all APs connect back to SZ quickly ).
Now go-ahead and change the IP address of SZ100, please wait few minutes as because certain services would restart; after a while SZ100' GUI should be back APs would show up.
There isn't any document specifically for this, but these should be sufficient, should there be any please keep this thread updated.
Regards,
Abilash PR.