Alienware Alpha / Steam Machine - Five Blinking Yellow Lights Issue

I would say CMOS battery needs replacement.

The 5 Blink yellow alien of death. I did the power drain as described didn't work. So I did a power drain with everything disconnected and held the button for about 2 minutes (instead of 1). Plugged everything back in, pressed the alien and presto! We now have power. Great right? Except now you have an RTC is reset message saying strike F1 to continue or F2 to run setup utility (Which means you have to connect a wired USB Keyboard and mouse to reset the setup.   HOWEVER if you don't replace the battery it will fail again if power is shut off.).

Amazon.com: CMOS BIOS BATTERY for Dell Alienware Alpha ASM100 i3 i5 i7 Desktop Steam Machine CR2032CL-23-2: Computers & … 

The battery is on the back side of the mobo.

http://downloads.dell.com/Manuals/all-products/esuprt_desktop/esuprt_alienware_dsk/alienware-alpha_Owner%27s%20Manual_en… 

Removing the Coin-Cell
Prerequisites
1 Remove the base cover.
2 Remove the top cover.
3 Remove the hard drive.
4 Remove the processor fan.
5 Remove the processor heat sink.
6 Remove the processor .
7 Remove the video-card fan.
8 Remove the video-card heat sink.
9 Remove the memory modules.
10 Remove the wireless card.
11 Remove the system board.