I suspect that the problem here is a language problem: Swedish/English/Lithuanian!
I'm going to say that I'm sure the problem is a sticking microswitch on the right side of the bonnet slam panel causing the |ECU to think that the bonnet is open and it is warning you accordingly.
https://www.volvoforums.org.uk/showthread.php?t=279884 where I posted my experience will apply. Liberal spraying of a good quality penetrating and lubricating spray may solve the issue and the paper clip work around will stop the warning. If it's intermittent it will mean that the switch isn't entirely seized and lubrication should solve the problem.