Hello
Either the firmware is corrupt or hardware related issues. Please try the hard reset method given on this link http://www.satechhelp.co.za/8963/Hard-Reset-Mobicel-Vivo?show=8963#q8963. If that does not help' replace the firmware with another one of the device model. You will have to find someone and we can help backup their ROM to fix yours. Remember' it can also be hardware related problems it is not that simple to tell the exactly fix in your case.