The element has become too hot and has burned itself out - a part of it carrying live power is touching the earthed shell of the urn - this is why the power is tripping out - as a safety precaution to prevent electrocution.
Amazon or somebody may sell you a new urn - repair may be difficult, costly and take longer than you would wish.
Do not attempt to use it - give up on the plugging it in.
Peccavi
November 2010