IANAL: The short of it is that unless Samsung can prove that it's the software's fault that the malfunction is there, they have to repair it.
A blown efuse is just as much proof as the 'warranty broken if removed' stickers, which is none.
There's lot's of cases online where Samsung/resellers try to stop people but as long as you are persistent and don't just accept them not wanting to fix it they will repair it.
There's also some cases of going through the small claims court to handle this (which doesn't cost anything if you win) Small claims court
Also: This ONLY applies to the normal EU warranty which you always have, any extended warranty does not need to repair your device if you've rooted it.