We may need more information to properly help you. From what you posted, it sounds like the computer is able to power on, but that it gets to the end of the startup progress bar and then freezes or crashes. If this is the case, the most likely cause of the issue is a damaged file system. Try booting into [link|https://support.apple.com/guide/mac-help/use-macos-recovery-on-an-intel-based-mac-mchl338cf9a8/mac#:~:text=Restart%20your%20Mac.,other%20apps%20in%20macOS%20Recovery.|Recovery Mode|new_window=true] and running [link|https://support.apple.com/en-us/HT210898|First Aid|new_window=true] on the internal storage drive. If that doesn't help, try booting into [link|https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac#:~:text=Press%20and%20hold%20the%20power,The%20computer%20restarts%20automatically.|Safe Mode|new_window=true]. If that doesn't help, you may need to [link|https://support.apple.com/en-us/HT204904|reinstall your OS|new_window=true]. Good luck!