computer would shut down, flash the bios, and reboot.
Most likely cause is a bad BIOS flash. I have had little experience with retail units that have a bad flash (I only build my units), but I suggest that you Google around and see what you come up with. You can try resetting the BIOS to back to default, it might work on an older BIOS chip but I would not put a lot of hope in it. At least you won't hurt anything.
Not to irritate you, but my experience with computers is to leave the BIOS alone unless there is an important reason a flash is necessary. Double-especially any of these programs that claim to do it for you automatically, including finding the correct flash download off the internet. Unfortunately, those that have their computer bricked by these cheesy outfits find that they will not help you if there is a problem, as in your case. Go on the Dell website and see if a flash for your unit is available from Dell; if it is not, then that is a strong indication that any other source will not be trustworthy. These retail manufacturers are not dependable on supporting old units, so hope for the best.