I found myself doing an out of hours reboot of a Windows Server 2008 R2 server which would not shut down via the OS. The server is an HP Blade BL465c G7 in a c7000 enclosure. So I performed a cold boot via the HP iLO menu as I normally would. I then started to worry when I saw the orange indicator light on the blade enclosure rather than the normal powered on green light and no errors in the IML log.
I went into the Remote Console, the Integrated Remote Console and the power options menu in the Onboard Administrator and clicked "momentary press" which would normally power on the server. None of them worked - the light was still orange....
I then did some research and found that if you SSH onto the Onboard Administrator, you can perform a reset command, which effectively removes and reseats the blade. You can do this using PuTTY or any other SSH client.
Once you SSH onto the client, type in the normal username/password you use in the GUI to authenticate, make sure you identify the server correctly by the number which appears to the left of the server name in the device bay, then type:
reset server X (where X is the server number).
Read the warning
Type YES and push enter
The blade will disappear from the chassis, like it would if you removed the blade physically, and after about 20-30 seconds it reappears and it is already powered up.
Saved a night time drive into work :)