Does F2 work for you? Can you get into BIOS and change it back? Possible I guess you might need to use the Windows Migration Tool to do a full clean install if the hard disk is messed up. Also you can use that tool to get to a Command Prompt and then try rebuilding the MBR. Windows 10 and 11 should work the same way, see [URL] 
My pc is stuck in a loop and I've tried everything.
XPS 8940, stuck in reboot loop