I had very similar problems with the gauge cluster losing power and all kinds of lights going on used to happen in the middle of my drive to school and wouldn't go off until I did the same thing you stated to clear it up when I got my car a few year ago. if I remember right there are two grounds in front one under each headlight. noticed how corroded and barely attached they were when I swapped out the headlights and just decided to re-splice them since they were beyond the "cleaning point" lol. that made the problem much better use to have to deal with it every day and now only happens about once a month and only on startup I probably have another bad ground somewhere but it doesn't annoy me enough yet to diagnose and fix it haha. may need to take the front bumper off as well I remember I had mine off for something else. but might be able to do them with just the headlights out.
