Facing issue while opening ipad. It only displays "slide to Upgrade"

Hi there !!

I have got this ipad 4 Wifi model. I had made few updates to this ipad, last year and have forgotten to upgrade since then. It was having ipad 6/7 ( not sure of previous version though). I was not upgrading for obvious reason that there might be some issue after doing that. But unfortunately my mother made the update to my ipad ios version to ios 9, recently.

Currently, the upgrade has affected my ipad. It is stuck in "slide to upgrade" screen where nothing happens after that. Note, I have not made any backup of the data present in it.

I wanted to have the data retrieved as well. I am ok, if it can be reverted back to any of the previous version which will work on my ipad.

Thanks in Advance

/P