Here are steps to address your issues:
1. Boot your Mac into Internet Recovery Mode by holding Cmd + R during startup.
2. Open Disk Utility from the macOS Utilities menu.
3. Select your Mac's internal hard drive and click on "First Aid" to repair the GUID Partition Table.
4. Allow Disk Utility to complete the repair process and then attempt to restart your Mac to check if it boots into macOS successfully.
If the above steps do not work, please try to clone the disk to an external HD to ensure your data backup:
1. Connect your external USB hard drive to your Mac.
2. Open Terminal from the Utilities menu in Internet Recovery Mode.
3. Use the 'dd' command to clone your internal disk. Replace diskX with the identifier of your external drive.dd if=/dev/disk0 of=/dev/diskX bs=1m
4. Confirm the command and wait for the cloning process to complete. This will create a backup of your entire internal disk, including all partitions and data.
5. After completing these steps, attempt to restart your Mac normally and check if it boots into macOS without errors. If you still encounter the issue, it is suggested to contact for technical help.
You can also refer to How to Use macOS Recovery Mode on Mac (M1/M2/M3 Mac)?
