So far I've repaired 4 out of 6 successfully; the other 2 had board problems. I've also.had some DOAs and units which worked then went dead shortly afterwards but never your scenario.
I always use Vida to test the unit afterwards. The only other code reader I know of that can handle this system properly is the Autel EU702 . The resting output voltage of both sensor 1 & 2 should be closer to 1.4V. Even 0.2 of a volt difference can upset the circuit according to Jack. I was lucky with the 4 I've done not to have issues but the last one I repaired has a hesitation b/w gears which a new ETM solved (though it had no codes)
Hope this helps.
Current cars: 1995 850, 2000 V70 non turbo, 2001 V70 XC project, 2002 S60AWD
What we used to own:1987 740 sedan, 1989 740 turbo wagon, 1985 760 V6, 1995 850 wagon, 1999 V70 project car.
In forum posts please call me Mike