The thing that’s a little scary here is that the power lock circuit is ‘hot’ even with the key off. So if you do have a problem, it could develop into a real catastrophe at any time of day or night. Personally I don’t think the extra 5 amps will make that much difference—a direct short will still blow a 20A fuse mighty quick!
Does the fuse blow only when you use the lock, or do you just notice that it doesn’t work? Also, when you look at the blown fuse, is it just melted, or does it look like a tiny firecracker has gone off inside it? If it’s just melted, you have an overload. If it looks like it really BLEW, then you have an intermittent direct short somewhere.
Definitely keep an eye on it.