Buttons no longer work after camera was submersed in beer

Beer is inherently sticky and sugary when it dries out and presumably that's what has glued up your buttons. Personally I would usually try to dismantle the affected part and clean carefully with cotton wool baby buds and a water based cleaner -- but this may not be practical.

Without dismantling I would start by removing any batteries, Then try to clean the affected buttons using a wate based cleaner spray very sparingly and leave to dry for a couple of days in a warm place.

A petrochemical/alcohol spray will dry quicker but may not be so effective on the sugary stuff -- use Isopropanol if that's available (because it probably won't affect the plastics).

You're probably referring to a Torx screwdriver -- these can be hard to find in small sizes (electronics manufacturers prefer to keep your fingers out of your stuff).

The other problem is that modern assembly also uses edge clips moulded into the case -- and these break if you don't know where they are.

When disassembling laptops I prefer to start with two similar broken ones, knowing I'll scar or break the case of the first just working out how to open it.

Ideal if you can find a similar model camera that's non-working because you can also swap parts.

Alternatively you may be able to find a repair manual on-line.