Tablet won’t start

Hello helpers

My Sony Xperia tablet Z had a problem with the charging port, after replacement the battery is now fully charged but the tablet wouldn’t start!!The only sign of life is when connecting the charging cable, so the screen stock in blank just after the logo screen and the 100% charged battery screen.

I’ve tried all the ways to reboot it but nothing worked, power+vol up, power+vol down, power+ 2 volume buttons or even disconnecting the battery!!

It seems like that the power button is not working! But even with connecting the power cable it’s not working!!

Any idea

Thank you