A critical software update is requieres for your Mac. Error encounter

That error message indicates that macOS is unable to upload the hidden EmbeddedOS image file to the Touchbar. It may mean there is an actual issue with the Touchbar, and/or the Logic Board. It could also be due to some other hardware failure which is affecting the ability to upload this software to the Touchbar. I have seen the built-in iSight Camera have a problem where it causes this problem....no idea why. For some reason macOS will refuse to boot normally if the EmbeddedOS software is unable to upload to the Touchbar...seems a better option would be to report an error & continue booting normally, but that is just me.....what do I know.

When booting into Safe Mode, it seems to allow booting the Mac with a defective Touchbar so at the very least users can make sure they have a recent backup and possibly continue using the laptop in a degraded state until the laptop can be repaired.

Safe Mode does some disk housekeeping but some of those tasks need time to complete. I found htat out weh working through some issues with changes I made tohte aftermarket SSD in on eof my older MBPs.

Try letting the computer sit in Safe Mode for about 30 minutes without using it and see if your can then get a normal boot.

We are not Apple, just users like you, and cannot speak for Apple in any way.

If the official Apple representative has stated the main board needs replacing, we as a technical assist community cannot dispute that. Even if a single tiny component failing were the cause, the fix is to replace the entire board. Apple does replacements; not true repairs.