Hello,   Do you know if the BMC is responding? If it is, I would reboot it from the web interface. If not, I would hold the i button for 30 seconds to make it reset. If that also doesn't work, I would look at a power drain of the system by shutting it down, unplugging it from power, then holding the power button for roughly 10 seconds. You can then bring it back up as normal.
Hi I have a PowerEdge C6220 with four nodes. I just updated all to FCB v1.21, BMC v2.53 and BIOS v.2.5.7. Now the fans run at 16k+ rpm despite a total power usage of ~500 W and temperatures below 45 degC. The BIOS further says: MRC v2.0.00005, ME v2.1.5.73, VBIOS v0.96.00. Any clues how to fix this and/or change the fan speed control? 
PowerEdge C6220 Fan run at full speed