Before you start, read Important safety information and print the following instructions.
The cables for all connected devices are connected correctly and securely.
All components have been reassembled correctly.
All connected devices that require ac power are connected to properly grounded and working electrical outlets.
All connected devices are enabled in UEFI BIOS.
Use an antivirus program (if any) to see if the computer has been infected by a virus. If the program detects a virus, remove the virus.
See Troubleshooting and diagnostics to resolve the problem you are experiencing, run the diagnostic program, and recover your operating system.
If the problem persists, contact Lenovo. See Help and support.