Status Of Second Will

My father made a registered Will in 2002. He died in 2015. His qualification was Graduate. He was a neuro patient 2 years before his death. After his death my brother told us that the father has made a registered Will 4 months before his death in 2015 - in favour of my brother. On Examination, this Will has following lacunae --- 1 - This Will is not signed but has thumb impression.According to my brother and one of the Witness of WILL , my father didn't sign because his hands were shaking.But there is no mention in the WILL that he didn't sign because his hands were shaking. 2-The Witness to Will are a - First Witness is friend of my Brother's brother in Law b- Second Witness is labour of my Brother's brother in Law Factory. 3- Many property details are incorrect. 4 - There is no mention of earlier Will.But it says that this is the first and last Will. 5- It doesn't cancells the earlier Will. What is the status of this Second Will made in 2015.