When your hot end is in air, can you command the printer to extrude some plastic? If so, does it extrude with or without the clicking sound? If it does click, slow the extrusion speed down, e.g. G1 E20 F100 - which will extrude 20mm of filament at a reasonable speed. If you can extrude filament without the clicking sound, re-check how far your nozzle is from the bed. If it is too close, your printer will be trying to push filament out against the weight of the X carriage resting on the bed as there's no room for the plastic to squeeze out. Make sure your print head is a reasonable distance above the bed by placing a piece of paper under the nozzle and adjusting the Z axis home position to a point where you can move the paper, but feel slight drag from the nozzle.