Some of this has already been covered, but...
They ran a background when I was hired.
Please clarify what "ran a background" means. I assume you left off the word "check," but not ever background check is the same. Some of the prior responses seem to assume that your background check included (or maybe was limited to) a credit check, but I don't think that's a necessary inference from what you wrote. Were you given a written report regarding the background check?
There are some blemishes on my background
For example?
they did a random background check on me last week and let me go because of it.
Was this new background check identical to the one that was run two years ago? Were you given a written report regarding this new background check? What exactly were you told was the reason for your termination?
Nothing on that report has changed in over 7 years.
Disregarding the odd reference to "7 years," how do you know this? Again, did you receive copies of written reports regarding both background checks? Or are you just assuming nothing has changed? Were the background checks conducted by your former employer or by a third-party company? In what U.S. state did you work for this employer?
They saw everything when they first hired me.
"They" being who? Your immediate supervisor? The HR manager? Are all these people now the same as when you were hired? Has your former employer's policies changed in the two years that you worked there?
I think I've included questions asked by others, but please answer the questions I and the others have asked.