Sorry for the trouble. There are two ways to reset the name: Through the meter settings (as you already tried to do) and by rewriting the firmware. I recommend changing the name through meter settings, although this seems to have failed on your device.
What is the battery level on your meter? One known issue is that flash writes within the meter can fail if the battery level is low. Perhaps that’s the cause of the corrupted name field you’re seeing. Can you replace the batteries in your meter and try setting the name again?