Did everything appear to go smoothly when you did the firmware upgrade? Did you have any problems or have to attempt the upgrade more than once? Did you make any changes to the ethernet setup in rp2?
error 1383 means that the M1 in having trouble communicating with the xep. I would check the serial cable between the M1 and the xep, check all of the ethernet settings in rp2 and re-send them to the elk. Watch the lights on the xep to see if the power supply is constant. Try pinging the xep to see if you can communicate with it from the LAN side.
It may be that your firmware upgrade failed but I would exhaust all other possibilities first. It could be something co-incidental like a power or cable problem. This is one of those cases where it would be nice to have another known good xep to try in it's place.
I am not familiar with alarm relay. Does the elk report to them through the xep?
Mike.