Why do my nails feel hot when under the LED lamp.

Heat when under the LED lamp generally means that your application is applied to thickly.  This is called a Heat Spike.  It is caused by the energy created when the liquid matter turns solid.  You should avoid this and ensure that your application is applied finely.    If you find this difficult you could try warming your bottles of Base and Top Coat in a semi-hot bowl of water for a few minutes prior to application.  Thick applications are unstable and do not set all the way through and will lead to premature chipping.