I'd guess the drive is failing, then, or there's more information you haven't provided.
How to use Apple Hardware Test on your Mac - Apple Support
This is like the last attempt but tries to install the original version that came pre-installed from the factory.
Internet/Network Recovery of El Capitan or Later on a Clean Disk
If possible, back up your files before proceeding.
You will need a fast, working Internet connection, preferably, Ethernet. If you must use Wi-Fi, you will be asked to select your network and enter the network password. This procedure will install the original version of macOS that came pre-installed from the factory.
- Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-Shift-R) keys until a globe appears.
- The Utility Menu will appear in from 5-20 minutes. Be patient.
- Select Disk Utility and click on the Continue button.
- When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
- Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
- Set the partition scheme to GUID.
- Set the Format type to Mac OS Extended, (Journaled.)
- Provide a volume name, usually "Macintosh HD."
- Click on the Apply button, then click on the Done button when it activates.
- Quit Disk Utility and return to the Utility Menu.
- Select Install OS X and click on the Continue button.