There are some possibilities for this problem that you will have to check out for 1) check the power ON/OFF button in the unit if its got internally loose this problem can occur.in this case the button needs to be re-soldered internally. 2) it can be the problem of the power supply wire of the unit.its getting cut in between in this case the power supply wire needs to be replaced.its bit time consuming job. 3) the main power supply board in the unit is got faulty.this is a costly replacement.not advisable.the cost of new board is near to new unit. This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya