OK, this is quite a bizarre situation which will take some longer describing, but I hope someone reads through it, as I can't even figure a relevant google query to find a similar problem, let alone a solution.
I got a smashed display replaced on my Xperia X. The display itself is working fine, but ever since I got it back from servicing, the following problem has been present: the display only worked properly if the phone got (re)started. The moment it got put to sleep with Android loaded and running - it could not properly get woken again. Press the power button, and all you get is a black screen. Yes, the screen is on, you can see some backlight bleed, the phone is awake, the notification LED is on, it reacts to incoming messages, but the screen is black. Nothing on it. Restart the device and it lights up as if nothing happened.
Some messing around the settings got me to the following: it works fine, if I turn off the tap-to-wake feature. Strange as it may sound. The feature itself is not working anymore anyway, but if it's turned off - the screen wakes fine with the power button. Turn it back on - and we're back to the blank, black lockscreen.
What do I do? Is it a hardware fault and should I take it back to the shop? Is there any possible SW solution? Any ideas, where to look?
At first I was thinking it's a power issue, since it had been off and without a charge for over a week. Now it's been charged overnight and the problem is still present. Makes no sense in my head, neither as a HW nor a SW issue, to be honest.
Help!
(tl;dr - Screen black when turned on if tap-to-wake is enabled. Screen working properly, if disabled. Phone owner in deep confusion.)
