Dell laptop power brick died and now bleeps.

My laptop power brick died on Friday - it took me a while to figure out why my screen kept going black after checking the power was plugged in at the wall and at the laptop. The weird thing is that the brick bleeps - it almost sounds like a ticking time bomb, even though it doesn't provide power (or turn the green led on) We tried various psu's at the office but it seems that nearly every type of dell laptop we have uses a different power brick that aren't compatible.