Question Please Help! Alienware 17 r4 will not boot.

Jul 23, 2019
I purchased a used Alienware 17 R4. When I received the system the mouse buttons did not work, so I replaced them & put the system back together. All was fine. I put the system to the side as I waited for a 2.5" hard drive caddy and hard drive cable connector. This was going to be added as an addition to the 256gb ssd that was already installed and running the operating system. After connecting the new drive cable and 2.5" drive I tried to boot the system. Unfortunately, it failed to boot. The keyboard lights up and the fans spin, but the display does not come on & I am receiving a single flashing trouble code for no ram found followed by a repeating bad cmos battery code. I pulled the ram & replaced it as well as ordered and installed a new cmos battery. Still, I am getting the same trouble codes. Any thoughts on what the problem could be? Also, I have uninstalled the 2.5" drive and drive cable to be sure it was not the problem. I have done the cmos reset as well. I am at a loss as to what to do next or what the problem could be. I have never had any luck with getting responses from these types of forums before, so this is really a last ditch effort. Any help would be greatly appreciated. Thanks!