Could be a battery voltage issue.Get the alternator and charging system checked.Possibly over charging with excess voltage.

Hi PJH

I'll share my Corsa D electrical experience with you, might help.

My wifes car had a windscreen replaced quite early on in its life. about a year later it started to suffer occasional odd electrical issues (dash lights might flicker slightly. the throttle pedal faulted and put the dash light on.)

I discovered rain water was creeping into the fuse box under the bonnet, from a poorly fitted piece of trim. I stopped the water getting in, removed the fuses and dried the fuse box out using plenty of electrical contact cleaner. this sorted the issues.

Another problem I had a few years later was during a service I noticed the grease on the battery negative terminal had all melted off, (only the negative terminal) I touched the battery negative terminal and it was too hot to touch (engine running) If I put lots of electrical load onto the engine the battery neg terminal would burn my finger! The earth leads were all clean, tight, corrosion free, secured etc. In the end I replaced the earth lead (battery to engine) and the terminal no longer got hot. Interestingly during the winter before discovering this problem the headlights, radio lights would flicker slightly. Also hot cranking of the engine was "different" slightly laboured. This was all sorted with a new earth lead.

Not the same symptoms as yours but I think its worth a look.