I know this is an old topic, but for other people this might be the solution for the same problem (for your own risk, of course). In my case, after changing the battery, the metric system switched to feets, while is was used to read the depth in meters.
First of all, the Suunto Companion is the same computer as the Tusa IQ-300, so if the same problem occurs by the Tusa IQ-300, you can use this solution too. This procedure will switch the metric system of the computer from meters/degrees Celsius to feets/ degrees Fahrenheit and visa versa.
Here we go:
- Open the back side of the computer, so that you can see the battery. DON'T REMOVE THE BATTERY! On the internet there are storry's that the computer fully erased his memory and tables, after the battery has been removed for to long time (more than 1 minute). In this cases the computer became worthless.
- Connect/push all of the three contacts on the front side of the computer with your (wet) fingers and keep them touched until the whole procedure has finished.
- While holding the contacts, connect the plus (+) and the min (-) of the battery for a very short moment (e.g. with a paperclip). This might sound curious, because by doing this you make a short-circuit, but it's the right way to fix this problem.
- After you've done this, the metric system will be switched and you can close te back side. Be carefull with the o-ring, ofcourse.
In my case the problem was solved, by doing this.
Good luck!
Klinkie
The Netherlands.