my plug in power meter just died , a few years earlier it had stopped working so i opened it up and found the built in battery leaking , so i cut the battery out and cleaned the electrolyte off the board.
this caused it to work again for a few years , now it has stopped working again , the electrolyte had soaked into the board beyond my ability to clean it off , and its beyond my ability to repair.
if your going to buy one of these power meters remove the built in battery immediately