Begin by checking if your battery supply is firmly attached to the back of your laptop. If this does not work, then plug in your power supply as this may cause the laptop to not turn on. If your device turns on after plugging in a power supply but shuts off immediately after disconnecting it, you have a faulty power supply. For a faulty power supply, go to the repair guide. (will add link to replacing power supply here)
If none of these solutions work, refer to the [[Dell XPS 15-L502X Troubleshooting|troubleshooting page]] for more solutions such as RAM failure or motherboard failure.