HP Sure Start detected an unauthorized change Boot Loop

[famont]

I can no longer get into the bios of the hp elitebook 850 g5

(HP Sure Start detected an unauthorized change...)

again and again trying to reset it with the key F1 or F2 ESC fails again and again.

I talked with the HP Support and followed their instructions, but the support said that the mainboard is defective and now wants to send me a cost estimate. There is really no way to get in with the BIOS

                                      at the last one according to instructions

1. Turn off the computer.

2. Remove the computer from any port replicator or docking station.

3. Disconnect all external connected peripheral devices, such as USB storage devices, external displays, and printers.

4. Unplug the AC adapter from the computer.

5. Remove the battery from the battery compartment.

6. Press and hold the Power button for about 15 seconds to drain residual electrical charge from the capacitors that protect the memory.

7. Put the battery back into its compartment and plug the AC adapter back into the notebook, but do not connect any of the peripheral devices.

8. Press the Power button to turn on the computer.

9. On the Options screen, select Continue to open Windows 10.

10. If a startup menu opens, use the arrow keys to select Start Windows Normally, and then press the Enter.

11. Reconnect each of the peripheral devices.

Ich komme nicht mehr in das bios der hp elitebook 850 g5
(HP Sure Start detected an unauthorized change...)

immer wieder neu hoch die versuche ihn mit der Taste F1 oder F2 ESC zurückzusetzen schlägt immer wieder fehl.