You can access Euclid's BIOS by pressing the F5 key at boot-up.
I recommend checking out the link below for a diagram on using a USB hub to connect a keyboard and mouse directly to the Euclid for accessing its BIOS.
Thanks Marty, i'll try this and report back with my results, others may want to do this too so might as well close the loop!
I've been looking for this as well. I went through all the BIOS settings and did not find a setting to boot on power-up. I am not using the Euclid battery pack in my testing set-up, and want the Euclid to come up with everything else when power is applied.
Oh dear, that doesn't sound encouraging. I'll let you know how my attempt goes.
Another way to start up without the power switch, if the BIOS supports it, is to use the Wake-On-LAN option so that it can be booted with a signal from a network.
I have checked the BIOS now, and tried the only thing that appears to be relevant to power-on after power is applied to it.
The BIOS category is System Setup -> South Cluster Configuration -> Miscellaneous Configuration
The option is called "State after G3" which is originally "S0 state". G3 refers to the event where power is re-applied after power-loss. The other option available for this setting is "S5". I saw later on in the BIOS S5 appears to mean battery charge state, so I don't think it's actually the thing I need. I changed the "State after G3" to "S5 state" and saved and exited the BIOS, then shut down cleanly, removed power, and applied power again. Nothing happened no boot-up.
Regarding Wake-on-LAN, that needs a hardware RJ45 ethernet controller and direct BIOS control over it at a low level. The Euclid's BIOS doesn't seem to have any Wake on LAN options, and it certainly won't work for Wifi and I doubt that a USB->Ethernet adapter will work properly because it only works once the Operating system is running and runs the virtual ethernet adapter drivers.
Therefore it appears that the Euclid may not ever be able to do this.
An alternative approach may be an Uninterruptible Power Supply (UPS) so Euclid doesn't power off in the first place when power is lost and the UPS' battery keeps the Euclid running til mains power is restored.