That could be a heat issue. Open the laptop, remove all dust, check if the fans turn, check the heat paste around the CPU (and if present the GPU). Might help.
when i switch on the laptop after a couple of days then it works fine for about 15-20 minutes, after that it shutdowns. when i again switch on the laptop it again shutdowns during booting within 15-20 seconds, and continues to shut down again and again.. It only works fine for 15-20 minutes, when it switch it on after quite a time.
anyone, please help, as my that laptop has became completely useless.