Unable to start up alienware x51

So some background information first. I notice my desktop had problems after a few months when it started to freeze occasionally when starting up and would give 5 beeps when I try to reboot it. Waiting for 5-10mins before trying to turn it back on normally resolved the issue. After a few months of this happening on and off (note that this did not occur on every start up, only some), I got frustrated and took matters into my own hands by finding what the beeps meant (stated to be replacing or reseating the coin cell battery). As I had no idea how to replace it (no IT knowledge here), I simply reseated it by unplugging the plug and plugging it back in by following the available tutorials.

However, this did not solve my problems as whenever I started my com afterwards, it would display 'no internal hard disk drive found' and to either reboot, enter setup menu, or enter PSA. Normally, I got around this by simply going to setup menu and exiting from there where the com would boot up normally. However recently, my com started to freeze more and this time gave 1 beep which I found out to be potential MB failure. I decided today to then update the BIOS to the latest version (14 I think?) but after updating, I can no longer boot up my com and it is forever stuck at the 'no internal hard disk drive found' screen. I am unable to contact my local alienware as they are closed whenever I try to call so yeah I'm left with the forums. I did run a PSA but it said that there was no errors found as well even after the extensive memory test that took hours to complete.

Note that the only thing I removed from the interior of the desktop was the graphic hook for the video card as I couldn't put it back on so I grew annoyed and simply left it out, not sure if it influenced the problems in anyway.