In my case, someone said me that the usb-type-c port didn’t work and some optoelectric components either. If someone knows how to find exactly the opto and how replace it, I would try to do it but it’s very difficult for me to do that in this moment. I’m thinking to throw it away to recycle but the screen is new and works perfectly. It’s a pity that there are no more info to repair this things. I don’ t know anything about the z500kl but it could be the same problem especially, if you don’t see charging icon when plug in to AC. But in my case I can’t hear anything either.
You could easily change the screen looking youtube videos (if you have some experience) and buying on ebay 50€ more or less the screen. You should be very careful replacing the screen, you must put glue to stick it very well, like it was, if not you could break it again. It’s very delicate.
You could open easily removing the 2 screws, remove the sd card and follow youtube instructions. When it’s open unplug the buttons connector. If the tablet stop rebooting is problem of the buttons if not I don’t know. The buttons could be easily bought on ebay. If the tablet stays switched off you could switch on with a small screwdriver touching in two pins at the back where you unplugged the buttons flex cable. You could also try how reacts when you charge and so on to discard battery, charging port…