Aurora R4, power on, not getting the Alienware logo and F2, F12 options

Any flashes on the Alienware head? Power button?

first thing to do is replace cmos battery and clear cmos settings by motherboard jumper

like chino said "Replace the coin cell battery, see #12 of diagram below.  Then clear CMOS via jumper, #13 of diagram below."

I've had a few systems in the past which didn't show the splash screen but you could still spam F2/F12 straight after powering on and it would get into the BIOS or Boot Menu. Have you tried doing this?

@redxps630​ I have sent off for a new battery and will do a reset once its installed and let you know the results. Thank you.

Replaced CMOS battery. No change to situation. If I let it logon to the UEFI enabled W10 OS it boots but if I try to get to the UEFI settings via shift restart, debug, advanced, select UEFI I do get the BIOS screen but the keyboard does not work.

I have tried a new, confirmed good on another system, keyboard and get the same.

I am completely stuck.

@MajorThorburn​ Dell Tech support advised me that  this device is in the End Of Life category and they have no parts so no fixes.

That leaves me with using what I have as it is still working just not how I wanted it.

Re: I do get the BIOS screen but the keyboard does not work.

have you already cleared cmos via motherboard jumper?

Some USB keyboards don't have a proper "DOS mode". You could look around for one that does, and it will likely work as it sounds like your current keyboard does not have a proper DOS mode.