Volume/Rotation Lock problems after battery replacement

Hi. I replaced the battery on an iPad Air which I’ve done a few times with no issues. This time, after closing up the iPad the volume was changing by itself constantly as if the buttons were being pressed.

I checked all the connections and everything looked fine. I decided to replace the volume/Lock Screen flex and initially, everything worked fine. The issue then started happening again as soon as I sealed up the iPad. No cables were damaged during sealing, and no pressure was applied on the flex.

I disconnected the digitiser to see if that could be causing any issues, but unfortunately not.

Has anyone else had a similar issue, or have any idea as to what could be causing the problem? Thanks.