there is also a reset button on the board itself - try pressing that a couple of times. Also one on the back of the screen - press that too.
And the 'remove and reseat cables' is always worth a try

The beeping is interesting - on computer motherboards there are a series of 'beep codes' that give a vague indication of any problems if the boar can't boot up.

Never heard of such a list of codes for 3d printer boards - but a continous beep is usually a memory issue - ob PC boards.
probably no correlation with a 3d printer board.

try the reset and cables. If still no joy, contact the people you bought the printer from.
And i wish you all the luck in the world with that :-)