I bought a house that has a prepaid meter. There were units on it and electricity was working fine. I have not been there for for 2 weeks and now the unit is off. When I switched it on battery low was showing. I replaced the battery. Now it comes on seems to be pairing successfully but only stays on for about 10 seconds then goes off. There are 22 units showing. What is the procedure to add prepaid units on this handheld unit. Anyone have a manual? I have never used prepaid before. This is quite urgent as I need to go there today and need electricity. Any help would be appreciated.