If you get a group together who hold 5%+ of the shares on issue,...

If you get a group together who hold 5%+ of the shares on issue, you can compel a meeting to be called.
At the meeting, you put your case if you believe the board is not working efficiently or in your interests. Then a vote involving all holders is held, and board changes suggested/enforced.
However, it is not as simple as it sounds. Not finding something is NOT grounds for a board spill. Also, you would need potential board members there to nominate..... who are you going to replace with who?
As an example, a group of us once had 60% of shares pledged to replace the board and put a viable project into the company.....
We couldnt get suitable replacements, or a suitable project, and if we had just spilled the board, the company would have gone into immediate administration.
A lot of work went into that, but we failed......and eventually the company failed.

Hey, it has been done, and with great success..... but as I say, you need the right people.
if you want to try it, get some skilled and well known people on board first, I'd say.

GZ