Ok so my phone is a studio xl2 and it's been running system check

My husband got me a Blu Studio XL2. I couldn't find the description so I picked the best one. My issue is it has been doing a system check or something, I'll have it in my pocket and every once and a while it will do this thing where it goes almost into a safe mode and runs tests on the phone, it tests the g axis, GPS, strobe light and anything else imaginable. I can't shut it off and I have to use the side vol buttons and power button to navigate as I can. Does anyone have any clue what is going on?