Little bit of backstory please?
Is this your first time trying to run it?
What's the exact message you're getting, and what led up to it?
In general, power cycling (i.e. unplugging) the obdlink can sometimes fix things, but that problem does not give this message.
If you've never paired it before, a wrong pin-code (or on some android phones, the pin code popup never shows) could maybe lead to a message like that. If so, try un-pairing then re-pairining.
Also rebooting your phone can sometimes fix things.