Damaged intrinsically safe equipment has to be repaired by somebody competent, usually an authorised repairer, but replacing batteries and the bulb in a torch is a user responsibility - that's why they're supplied with a key. The lock should be fashioned in such a way that releasing it cuts the power before the casing can be opened. I've seen loads of "dud" batteries thrown away because the user hasn't locked the case shut before checking that the bulb lights.
The big problem is that when you draw them from G10, no instructions are given with them (presumably thrown away with the packaging - after all, it's only a torch), so you have to work everything out for yourself - and each manufacturer has different ideas about how to lock the case.
Just to add, some torches have a sealed beam unit that is, indeed, a workshop job because the unit forms part of the outer shell.