While driving, they Bonnet Open watching displays with the red light on the gauge watching messages area. Also noticed the car alarm goes off at random moments, while parked. I suspect the two are related. Any ideas where to start troubleshooting?

I'd start with the switch in the engine bay ,

A common problem. I 'fixed' mine by shorting out the switch with a piece of Al foil (Kit-Kat bar !) in the connector.

The switch is under one of the latches I think.Look for the wires leading to a latch.

Thanks guys! I'll look into it this weekend when I'm back home with my tools.

I'm going to do the short-out trick this weekend. By the way, what is the trick to remove the sensor from the bonnet latch? Thanks in advance

Check by shorting the cables at the switch. If the warning does not go out, you may have an issue with the earth. The bonnet switch uses the "G1" located behind the headlamp, same side as the air box

Cheers
34by151

I was trying to be slick by trying to disconnect the cable without taking off the bonnet latch. However, after removing the latch I was able to get enough purchase to disconnect the cable. After I put a paper clip piece into the connector, taped it up, job done.