iPad goes into bootloop when power button flex cable is connected

After I (more or less) successfully replaced the battery on my iPad it would go into a boot loop. After searching around for a bit I found a possible solution, someone suggested disconnecting any flex cable besides the screen and trying to boot it up, that worked for me. Afterwards I connected every flex cable to check which one was faulty and I found out that the power button flex cable was causing the problem. Now before I spend any more money on this 7 year old device I wanted to ask if there is a way to check wether the flex cable itself is the problem or if I damaged the connector on the mainboard itself. If there is no way of checking I'll just bite the bullet and get a new power button.