Venue 11 Pro does not turn on

model: T06G
This tablet has been giving us problems for two years now. Sometimes after manual shut down or automatic time-off, the tablet does not power on. The current power off session has lasted three weeks. Even though the device's charger works well, we ordered a new charger to be certain and it worked with other devices but not the Venue 11 Pro in question. We replaced the battery Type 9MGCD and still the device will not start.
One more point to note: the power light does not turn on when the device is charging. 

What should we check for, or how do fix this tablet?