Samsung's system does not allow this so the only way back is to replace the board the firmware is on.

There is some issue with Samsungs over the last month or so that shutdown when they connect to the internet.

Be sure to unplug all HDMI cables, then remove power for 5 minutes. Reapply power then do the usual factory resets. Do not connect it to the internet. Apply one HDMI connection and retest.