"Do over".
Is all important data backed up to locations away from the problem computer? Verify that the backups are recoverable and readable.
Verify that the correct drivers are installed for the keyboard and mouse.
Try running "dism" and "sfc /scannow" to find and fix buggy or corrupted files.
https://www.windowscentral.com/how-use-dism-command-line-utility-repair-windows-10-image
https://www.lifewire.com/how-to-use-sfc-scannow-to-repair-windows-system-files-2626161
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Re-read and review the entire motherboard's User Guide/Manual. Double check all connections and configurations. Do the same for all other component documentation.
Then following the procedure provided in the motherboard's User Guide/Manual, reset the system.
The objective simply being to allow BIOS and the OS to start afresh, find all installed devices, and boot accordingly.