right - you have it the wrong way round.

Tightening the levelling knobs LOWERS the bed and moves it away from the nozzle.

Loosening the knobs raises the bed and puts it nearer to the nozzle.

Normally:
Anticlockwise - left to roght. lowers the bed.
clockwise: right to left, raises the bed.

The jackhammer noise is caused by the endstop NOT being triggered.
Either:
1) you plugged in into the wrong socket
2) it's a faulty endstop
3) the print carriage is not triggering the endstop - ie: endstop in wrong place.