The National Institute of Technology and Evaluation is investigating 31 cases of overheating regarding the portable, 23 of which happened in Japan. No injuries have been reported in those cases, but in each one the overheating damaged the PS Vita power cable connection slot.
Sony Computer Entertainment Japan reportedly blamed the incidents on liquids or other objects in the port while the systems were charging.
Because the company doesn't believe the hardware is faulty, it will not be issuing a recall, and those with damaged systems will need to pay for their own repairs.
A Sony representative confirmed the damaged system reports, saying, "The cases were caused by partial short-circuit on the multi-use port of PS Vita and USB cable due to small particles or liquid attached to it. We believe this is not [a] product oriented issue. The short-circuit damaged the Multi-use port, resulting in being unable to boot the system."