Once I remove the 3 screws on the bottom of the kettle, how do I pull the bottom off

Appliances like these are not designed to be opened. If it is faulty it should be replaced by a new one.

Replace the contact assembly. Call the manufacture about how to purchase their parts. I would also replace the one on the tank at the same time since they work together.

Buy a new kettle as the labour of a repair will be more than its worth.

Hi your element is blown

This happened to my Alessi kettle also. I changed the fuse in the plug but the kettle is dead! Red lights are on but the heating element in gone. From what i can gather parts are not available to fix it.

It's possible it can be fixed. Ours also no longer clicked. I took it apart and found that the flat plastic piece in the handle that activates the circuitry in the base had broken away from the rocker piece in the base. Fortunately the same flat plastic piece conveniently had a couple of holes in it in a helpful location. I looped some wire through the holes and also around the bottom rocker piece to hold the two pieces together.
I reassembled the kettle and tried it out and it now works fine! Problem fixed.
To disassemble, take the four screws out of the bottom of the kettle. (You'll need the appropriate star bits to do so.) Put those screws in a safe location... Lift off the bottom plate.
Now, the plastic for the handle is held in place by the typical notched clasps used by so many plastic appliances. You unsnap the clasps by CAREFULLY inserting a straight blade screw driver between the handle plastic and the kettle and GENTLY prying the handle plastic away from the kettle. You'll hear the internal clasps "popping" as they snap loose. You CANNOT take the handle all the way off this way. You just loosen it. Now, the top of the handle is a separate piece. Do the same for this. The top will pop completely off.
Next, GENTLY remove the lid. You can slide it a bit up and away. It's a tight fit, so you need to use a little force, but not too much.
Once you've done this, there are two metal pins that hold the main part of the handle to the kettle. They have a little ridge around the top that you can use to pry them out with your fingernail. Once those pins are removed, the handle will simply come off.
BE CAREFUL! The various parts in the handle are now loose! If you aren't careful they'll fall off and you'll have to figure out how to reassemble them.
Now, you'll notice the long flat plastic piece running down the side of the kettle. That piece was hidden behind the handle. It is SUPPOSED to be fastened to a rocker plate at the bottom. If you look at the end of the flat piece at the bottom you will likely see what I did. It had just disconnected from the rocker plate. Take some wire and wire the two pieces together using the little hole-like slots at the end of the flat piece. Just loop the wire through the hole and down around the rocker plate piece exposed inside where the handle is.
While applying this wire, it will be helpful to put a little masking tape across the various handle pieces to keep them from falling off. This is important because you'll probably be wiring the pieces together with the kettle on its side like I did, and the parts will fall off if you aren't careful. When you are done wiring things together you just remove the tape.
Once you've done this, reassemble the kettle in the reverse order you disassembled it.
You'll notice that once you've wired together the two separated pieces, pressing the switch on the top pulls up on the flat plastic piece which pulls the rocker plate which closes the circuit in the base.

get it serviced the think is the heating coil may have got burnt out if you need to replace it remove the cover below and take out the coil carefully with the terminals ..now replace the coil of same wattage usually 700watts in the same way
there can also be a problem with some wire got burnt due to heating .try to find the wire located near/attached with the heating coil and check whether everything is correct

sounds like there's water in the element. Empty it out and let it dry out completely for a few days, and then try it again.
If the element is a concealed element (ie- you can't see the coils when you open the lid up) then there's probably a water leak into the sealed compartment.
Contact the manufacturer for a recommended repairer.

Sounds like the switch is weight sensitive. A safety feature to prevent overheat as contents run low? The baseplate is probably not moving freely enough to move accordingly.