If the pager is not powering up; I would send the pager in for testing. It could be one of the copper connectoins points need to be replaced or reattached to the main board. Prior to sending the pager in; please take a moment and confirm you are useing a charged Durcell or Enginizer Battery and you are installing the battery correctly.
If the pager is powering up but, nothing on the display; the pagers LCD (liquid crystal display) needs to be replaced.