Sorry to hear that. We followed the manual offboarding process, for which the first step was to turn off the "sense" service, which we did via WinRE.
https://learn.microsoft.com/en-us/defender-endp...
If you can re-enter WinRE, please run these commands and re-enable Sense (ATP):
reg load HKLM\SY2 C:\Windows\System32\Config\SYSTEM
reg add "HKLM\SY2\CurrentControlSet\Services\Sense" /v "Start" /d "3" /t REG_DWORD /f
reg unload HKLM\SY2