Troubleshooting: My computer won't turn on has links for resetting SMC or PMU with various models. You didn't say which kind of laptop you had so that article should give you a link for your specific type of computer. For a summary of SMC, read Intel-based Macs: Resetting the System Management Controller (SMC).
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
| 
