Problem to start my hipad pro

now my hipad pro does not turn on properly. when I turn on the screen flashes from black to gray at approximately 1 second intervals.
a month ago it began to start regulary only after a few attempts. Now it doesn’t start anymore. if I click the power button 3 times quickly, the tablet vibrates, but don’t start. Does anyone know what i can try to do to get it back?

Hello, you can contact the mailbox of for processing, thank you