Why my 2017 iPad pro rebooting and show green and black line?

That doesn’t look healthy!

We should back up here and you should tell us what has happened to the iPad in the days and weeks leading up to this issue. Was it dropped, repaired or came into contact with water? If you just had random green lines but everything else worked, then it could be an LCD connection issue. However, the boot-looping points to a more serious condition of the logic board.

If you want to attempt a DIY repair, then open it up and check the connections. Keep in mind that you have to be very careful when removing the screen because if you damage it, it is quite expensive to replace. While it’s opened, closely inspect inside to see if there are any signs of water damage.

At that point, you may need to consider if you try a replacement screen to see if it solves the problem but with the cost of this part, it’s usually better to have a shop look at it and eliminate the screen issue for you at little or no cost.