Power on/off dual function problem
The 3u MDS is a two CPU modules in one chassis design, but it has only one power on/off button (located at front right top) affecting both sides.
Sometimes it might be required to power up one side (because it was off for whatever reason) and leave the other side alone which is already on, but having only one power on/off button complicates things a bit. In such a case when pressing the power on/off button momentarily will power up the side that is off BUT on the side that is already on will initiates a Linux Desktop GUI prompt for shut down countdown sequence (see screenshot), this needs to be manually aborted before the 60 seconds count down expires, if this does not get aborted Linux will initiate a shut down sequence and turn of that side.
Abort shutdown workaround
Have a KVM monitoring the side that is on, you should be on the Linux Desktop, confirm you have keyboard and mouse control. Press the on/off button momentarily, this will power on the side that is off but also cause a popup dialog box for the shutdown count down. You must click on the Cancel within 60 seconds to abort the shutdown.
Long term BIOS solution
If the BIOS is set to auto power up, then simply unplugging the module and reinserting it will accomplish the power off / power on without having to press the power on/off button.
Change the BIOS settings
Reboot the side you want to change, at the BIOS press ESC to bring up the BIOS setup Utility.
Select Advanced > Boot Features > Restore on AC Power Loss. Press return to bring up the options, select Power On.
Press F10 to Save the configuration and exit (reboot).