Why does my ps vita shut down after being in standby for 14 seconds

Why does my ps vita shut down after being in standby for 14 seconds

so ive ran into this problem recently where i turn the vita off so its in standby mode and after 14 seconds it shuts down the vita. i left the vita on charge for a hour or so to make sure its not because the battery is too low but still happens. my vita is jail broken dont know if thats got anything to do with it. here is a link to a video of it. thanks for any help