Why not power Up?

Hi everybody, I've a question concerning power up of my Tab 3, with battery up to 95-98% of charge in any reason after sleep time (not measured - 1 to 2 hours) the Tab does not start.

I try all common know issues to wake-up without success. At the end I open the box and disconnect the battery (white connector) then I disconnect all ribbons connectors and put back in place. Finally I reconnect the battery and try to power up with power button .... And the Tab 3 comes up ! Start correct, bat 98% and I use it.

My concern is why, time to time, it is not possible to wake up the tab ?

I've to do the same think now tree time to power up my tab 3 !

Any idea on this problem ?

Thanks in advance ....