420 case against employee for following instructions of MD.

I was working in a company for almost 40 years. During the last but one year of my employment, I was asked to sign a cheque [over phone] by the MD This cheque was given to a third party with whom the company had subscribed for raw materials. The said transaction resulted in a huge loss to the company and the supplier is now absconding. The inside fact is that there were dealings with the MD and the supplier. I wasn't aware of this fact and I was told that there was a Board approval for the same. There was no written instruction given to me and the MD said the same phone and assured to present me with the documentation in time. I then went and deposited the cheque with the bank, the bankers have known me for about 40 years and hence gave their approval for the transaction even without documentation based on trust. There was a domestic enquiry and an enquiry by the lokayukta. the former is still waiting judgement and the latter has cleared me as innocent. The case is in summons stage before the magistrate and I want to prove that I had no part in these dealings. My ex-MDs have all called me and vouched for my honesty. Five months after this suspension [about 8 months before my retirement], I was diagonised with cancer [2014] and have survived it. I unfortunately have no proof or anything. The company is not willing to provide any documentations despite requesting several times and despite writing to the current MD. Last year, I was told that the company has filed an FIR against me. I have been granted anticipatory bail. I now want to get a thorough clearance at the earliest, cause I have not committed any fraud but merely followed instructions [ I was ordered to, when I questioned how it could be done without Board approval]. So, kindly suggest and help me.