turning on and off without me doing it

Remove batery. After 3 minuts replace batery. Power on. Let set 3 minuts. If it continues try to download clean master from google play store and run the app. Note uninstall this app after use as this app is knowen to cause trubble to get you to download there other apps an buy there products. I use it on my devices an uninstall so i ashure you this is safe to do and using it this way will not harm your device as it has not mine. A last step is to hard reset, if you can, save all to sd card and make notes of all pass codes, contacts, memos, ect. and then unmount your sd card located along the outer edge or under the rear batery cover, mine is an HTC an the battery has to be removed to remove the sd card, so this could be the case as well with yours even thoe its not an HTC. Once you have extracted th sd card power off. Press and hold volume - wile powering on. Conferm the prompts. If this does not work your warenty may cover repairs. If ther is no warenty its time to send it to the bone yard. I hope this helps.