How do you do that?
Crack the case open, unhook the drive, put it into a desktop computer as a slave.
What you saw by the way is that there are two copies of the Master boot Record. They are supposed to be identical. Something caused the primary to get hosed up, so the computer read the secondary which was from the day before. Needless to say this is a major malfunction. It could be the drive, it could have been a USB write error, could have been many things. What it is now is a drive with seriously compromised data. There certainly will be data loss.
This is why I'm suggesting making it a slave in the desktop. You'll bypass any potential flakiness in the USB interface. I'd then copy the full disk off, whatever is still valid, then repartition the drive and format it again. Unless it was a hardware fault, the problem will be fixed.