Resk in opening demat account?

In most fare cases no trade broker can do any mischief with your cheque or your bank a/c.The signatures they have obtained will be for genine tasks like forms for Income tax matters,lawer verification,agrement in respect of the rules and regulation of the trader, the stock exchange requirements regarding pay in/out matters etc.Also track your bank balance periodically.You could have written less than Rs/1601.00 before you tender your cheque to them.