Out of curiosity, I ran your service app, although I do not need any of my apps with services. I moved back the line of code to the B4XMainPage as such:
Sub B4XPage_Appear
StartService(ServiceModule)
End Sub
I rebooted the tablet few times and it ran for me. I set the time interval to 2 minutes to speed up the process. Two minutes after the reboot, the service restarted fine. My knowledge in B4XPages is still shaky like many of us still, but that is what I observed.