Assuming there is nothing physically wrong I would try reformatting the SSD then reinstalling macOS. Here is the procedure using the Network Recovery option.
Internet/Network Recovery of El Capitan or Later on a Clean Disk
If possible back up your files before proceeding.
- 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 (will be the out-dented entry) from the side list.
- Click on the Erase tab in Disk Utility's main window. A panel will drop down.
- Set the partition scheme to GUID.
- Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
- 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.
It would be better to connect to the Internet using Ethernet instead of Wi-Fi because of speed and reliability.