If the desktop board supports the Intel® Management Engine (Intel® ME), BIOS downgrades are not recommended for security reasons. If a BIOS with Intel® ME must be downgraded and the downgrade will affect the Intel® ME version, the Recovery BIOS Update is the only method you can use.

Is it safe to downgrade BIOS Dell?

Generally, while Dell does not recommend downgrading the system BIOS due to the enhancements and fixes provided in BIOS updates, Dell does provide the option to do so. ... Caution: System BIOS may get corrupted if the BIOS downgrade procedure is not completed successfully.

How do I revert to a previous version of BIOS?

Turn off the power supply on the switch, move the jumper to the other pins, hold down the power button for 15 secs, then put the jumper back in its original place, and power on the machine. This will have reset the bios.