you might be right that the hookup has power connections. i haven't taken mine apart yet - that's the next step for me as i just verified that my problem is not the probe. a few weeks ago, i test drove a euro 200E and i noticed that it's display, though in centigrade, was bright and clear (which got me to tinkering with mine)...
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"