Optiplex 760 Won't Start Up

I'm going through a crate of desktops that was shipped to us. No information about them, so I can't ask anyone what this desktop's past was.

I'm getting mixed results while trying to start this up. Each one is a separate start, and happened on its own.

• Flashing amber power light
• Briefly flickering 1 and 3
• Solid green power light, beep codes, and solid 3 and 4 (after holding the PSU test button down for a few seconds)
• Flashing amber power light, flashing 1 and 3

Code Manual explains the codes. Maybe I'll be able to figure this out.

The error that keeps coming up the most often is flashing 1, 3, and amber power light. One error related to memory. There are 2 memory modules installed, and without both the test button on the PSU won't function. Not sure why that is.