Help with water heater switch

[quarkz 2]

Hi,

today my water heater suddenly can't be switched on - no light from neon indicator and heater as well. Last time, it happen once or twice but I tried to switch off and on and it worked. But this time it can't work.

How can I know if it's the switch that has problem or the water heater?

When I unscrew the switch, I found that one of the led black wires has came off. The other black wire is still attached to the top left hole (L2). Btw, mine is the CK CK200N water heater switch

1st of all, is it possible that the water heater can't be switch on if the led black wires came off?

2ndly, I tried to attach the wire which came off to each of the other 3 holes. Attaching to the bottom left hole (L1) works, with the neon indicator lightning up when I switch on - but sadly, the water heater doesn't switch on.

So anyone can help?

Thanks!