I have to press the unlock button multiple times before it unlocks the doors or trunk. I replaced the battery, but that didn't change anything. Does anyone have any idea if there's a solution to this problem? I'd be grateful for some advice. Thanks!

 

There are aerials for these. On my old Alfa Romeo i had the same problem and it was the aerial causing the problem not the fob. This was located by the ignition. (dont know if its the same on volvo's) it just needed playing about with to sort it out. It was a cable wrapped around the ignition barrel. Im sure all remotes work the same way. This could be your problem.