Follow the instructions in the following Apple article exactly....any deviation will result in failure:
How to revive or restore Mac firmware - Apple Support
The most critical parts are correctly identifying the DFU Port on the "broken" Mac, using a USB only cable, and making sure the Mac is completely powered down before attempting to access DFU Mode.
The USB cable must not support the Thunderbolt protocol at all, but only supports the USB protocols. If the cable connector has a lightning bolt symbol on it or any other markings to indicate Thunderbolt support, then you need to use a different cable. Some USB-C cables may be only for charging devices and may not support USB or Thunderbolt at all. The Apple USB-C charging cable is one option which does support both charging and the USB 2 protocols....this Apple cable has no markings on the connector (big fail by Apple not properly identifying the type of cable).
Here is an Apple article for identifying the DFU Port, unfortunately the article makes it very confusing & it doesn't help that Apple has not standardized the location of the DFU Port on its computers:
How to identify the DFU port on Mac - Apple Support
Using Apple Configurator can help you to determine the state of the "broken" Mac. It must show as "DFU" in order for it to work. Unfortunately you need to be running macOS 26.x Tahoe or macOS 15.7.x+ Sequoia on the host Mac in order to be able to perform the DFU Firmware Revive/Restore. Unfortunately using the incorrect versions of macOS or Apple Configurator will result in failure even if it appears to be doing the Revive/Restore (personal experience). Make sure to use the most recent version of Apple Configurator 2 from the App Store which is currently v2.19 (recently released shortly after Tahoe was made available).
If after several attempts the process still fails, then you most likely have a hardware issue with the Mac which will need to be repaired which will likely involve having the Logic Board replaced.