Battery drain after battery change ipad pro 9.7

Following situation: iPad Pro 9.7 was draining quickly. The old battery only had 50% capacity (coconutbattery). Installed a new battery from Aliexpress. The battery drained 95% overnight. Now Battery was replaced with an iFixit battery. The battery still drains 85% overnight (powered-off).

Additional info: When opening the iPad, I damaged the home button's flex cable, which means the touch functionality is not working. However, the home button still works.

Now my question: Can the battery drain on a powered-off iPad be caused by the damaged flex cable? Or what else could be causing the battery drain?

Thanks in advance.

MarkM