Your best route is to go into the BIOS and change the boot order, it'll likely read as boot drive for your HDD already there, so you should be able to see some options from USB port to the SSD you installed. More on reddit.com

There are several ways to start the Advanced Boot Menu. Route 1: Press the Start button. Click the Settings app from the Start menu. Select Recovery. Click Restart now for the Advanced startup option. Press the Restart now button on the dialogue box to confirm. This will start your computer in the Windows Recovery Environment. Route 2: Press the Start button. Press the Power button. Hold the Shift key down whilst pressing the Restart option. Route 3: Press Win + X Select Windows Terminal (Admin). Then enter shutdown.exe /r /o in PowerShell and press Enter. Route 4: Right-click anywhere on your desktop and select New. Click the Shortcut submenu option. Input shutdown.exe /r /o /f /t 0 within the location text box and press the Next button. Enter Advanced Startup Options within the shortcut name text box. Click the Finish option. Now double-click the Advanced Startup Options desktop shortcut to access Windows Recovery Environment. Route 5: Force shutdown and restart your computer using the power button about three to four times consecutively. This will make your computer enter the Windows Recovery Environment. More on reddit.com

You will need a Windows 7 boot CD or flash drive for that and run chkdsk /r via command prompt. See here . If it's dell, you can download it from Dell website using your computer's system tag. More on reddit.com

I solved it! It turned out to be the hard drive, as was said here. In the rare event that someone encounters the same issue, here is a very detailed response in a different sub who in fact did encounter a very similar issue: https://www.reddit.com/r/pchelp/comments/10zmvcj/unable_to_bootaccess_boot_options_or_bios/ More on reddit.com