Depending on the model, EXOR has a number of tricks like the one Hazey described to bring the unit up in confguration mode and such. For example, if you tap the screen once per second during a power cycle, the application won't load and instead the unit will come up ready to download a new configuration. EXOR's tech support isn't quite as good a it used to be, but they are still very knowledgable and helpful. Have you tried them at exor-rd.com?
If the comms LED blinks it usually means that the serial link to the PLC is dead. Check the PLC status, check for loose wires, etc. Do you have multiple pages on the unit? If so, can you change screens? Yes to both means that the EXOR itself is probably OK. Can you switch to status mode? Have you checked the diagnostics messages on puwer cycle? Have you verified the comm port on the EXOR is working by testing with another device? These are all troubleshooting techniques that identify where the problem resides.