It could be a broken spring inside the latch - mine failed and I had to rope the bootlid down. I pulled the latch apart (had to grind some rivets from memory) and found the return spring inside the latch had gone. Found a similar looking one and bodgied it up...still going after 2 years. I think it's fairly common.
"If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it." --T. Lehrer
"The secret of success is sincerity. Once you can fake that you've got it made." -- Jean Giraudoux