I have a PE R710 that started off with an iDRAC communications issue. We have iDRAC enterprise. I restarted the server and it said it could not communicate. I removed and reseated the module, it began working. Rebooted again and same issue. Removed and reseated and now it doesn't communicate at all. I have factory defaulted the server. Drained it of all power. Turned it back on and now the front LCD does not work and the fans run at 100%. I have left the server on for 5 minutes with no change. The server is getting power, when I press the power button the power light on the button goes green but the screen to the right shows nothing. I took the iDRAC module out and got the same results. I put the iDRAC module back in and connected to it and ran a ping. The default IP of 192.168.0.120 returns nothing. I waited 5 minutes again to ensure there was plenty of time for the module to initialize. I have verified that doing this does work on functioning systems. This system is out of warranty now, we do not plan on renewing. At this point I just want to know what happened. As we have many of these systems in production it is almost a need to know.
It sounds like the embedded iDRAC module has failed. In the worst case scenario, a motherboard replacement will be needed. Although it may not resolve the issue, you may also want to try clearing the NVRam also, If it does allow you back in where you can momentarily access the iDRAC IP, try to run the LCC(Lifecycle Controller) repair package from a remote system via the iDRAC web interface.
Lifecycle Controller Repair Package version 188.8.131.52, A00, Released 4/21/2014, restores embedded tools and utilities in the event of a hardware failure or flash memory corruption to the latest version. Such failures can occur for many reasons, including power loss or interruption during update process.