I quote from "Calicut: The City of Truth Revisited" by Prof. M.G.S. Narayanan:
As mentioned above, when the fear of humiliation and conversion to Islam gripped him, the king reportedly set fire to the powder magazine with his own hand. This happened on 27th April, corresponding to 14th of Medam, 941 ME (1766 AD) on Chitra day. The blowing up of the fort was symbolic of the end of Zamorin’s rule of Calicut which had lasted for more than 600 years. The Capital city from where his ancestors had marched out “to die, kill and conquer” was no more the same.
Thus the last ruler of the dynasty which treated Islam with dignity and promoted the Mappila interests in Malabar, perished due to the attack of a Muslim aggressor from Mysore. It goes to the credit of the Mapplia community that during three decades of Mysore occupation under Hyder Ali and Tippu Sultan, they refused,, with a few exceptions like the Ali Rajas of Cannanore,to join hands with the invaders inspite of appeals in the name of religion
