Iphone 8 lock button working weirdly

After a battery replacement on my iphone 8, the lock button is working really weirdly.

I can press it for long enough to turn off the phone, I can press it to display the lockscreen , but I can't press it again to lock the phone. The same goes as the AssistiveTouch, which can't do it either.

When I reseted foctory it (with iTunes on my mac) and configuring the phone, the button was working fine but now that I finished the config part, it won't work again. So it seems to be a software issue and not hardware.

Any idea ?