When a newer monitor like that (switchmode power supply monitor) squeaks, what you're hearing is the high voltage coming on, then the monitor noticing something's shorted, and it turning off.... then repeating, over and over again.
So you've got something shorted, it could be the HOT or the flyback, any large caps near the flyback... it could be the horizontal or vertical IC's, basically anything that woudl suck a ton of power. I don't know anything specific about that monitor, but I would guess your HOT or one of the large caps that will be attached to the HOT is shorted.