First check the battery compartment door. There is a micro switch that turns the camera off when you open it. If the battery cover does not press down on the switch the camera won't go on. Make sure that the battery compartment door covers the batteries so that the micro switch senses that the cover is closed. Or you can also send your camera to repair center if it is under warranty or you implement other troubleshooting ideas from [https://guideusermanual.com/product-name-eos-50d-manual&po=156725&lang=English|Canon 50d Manual] to resolve this issue.