Legal Notice from a company for not joining the organization.

Dear Sir, One of my friend working for a corporate(X)has accepted offer of another company(Y) but the current company didn't relieve him . During this period my friend given a resignation on mail and submitted the same to Y company. But verbally requested the Y company to extend the date of joining. But Y company created an mail ID in his name and given laptop to my friend before joining and taken sign on appointment letter on previous date. My friend signed the appointment letter as he was planning to join Y company after 45days . So he didn't able to deny to sign the appointment letter and compelled to sign it to obey the senior management people. But after 5 days he denied to join the Y company. He is continuing with the X company . Now he got a ligal notice from Y company that my friend joined their company and got all the company information & laptop during induction . They have asked to return the assets and confidential data immediately failing to this they will take ligal action both criminal as well as Civil including damage in court of law at his own risk and cost. They have also called upon to remit a sum of 55k toward cost of ligal notice. My friend has already submitted the laptop which was given during his joining date nagotiation period. Only mistake he has done that , he has signed the letter of appointment under pressure. Which contains different clauses. He has visited the Y company only for 5 days and on 7th day mailed he will not join the company. But on the basis of signed appointment letter Y company is claiming that my friend has joined and got a ligal notice from their lawyer. Please suggest.