Previous button link to first page

Hello All,

I have around 30 blocks of question and I have used table of contents but I don't want to use the TOC button as it appears on every page.

I just want the previous button of the first page of each block should take me to First block.

Eg: If I am at block 5th, it will take me from 5 to 4, I would like to avoid that and move directly to first block.

Please can anyone suggest any solution for this.