How to change battery on remote key fob

One of my key fobs doesn't work which I'm guessing is because the battery is dead. It looks like you can lever it open with a small flat-head screwdriver but I don't want to break it as I know these things can be expensive to replace.

I'm sure this must be quite easy but annoyingly (and not for the first time) the Audi manual makes no mention of how to do it (God forbid I might injure myself and sue!) Can anyone let me know how to do this? Thanks.

Try a small screwdriver like a jewellery drive in those small sets.

Or even check it by reprogramming it to the car. Unlock car with key, press unlock on fob, turn ingnition on, turn off and lock unlock on fob, should work, if not it may be the battery - says in handbook.

Thanks, I will give it a go when I get home.