Exclamation mark support.apple.com/mac/restore Mac Air M1

I have an issue with Mac Air M1, it was restarting again and again after a certain time interval.

Then it goes into recovery mode. I tried to reinstall macOS sequioa, but at last it failed, the laptop restarted and went into restore mode. Unable to open recovery mode

As I don't have 2nd Mac, I visited the new official Apple store in Pune, India, and they tried to restore it in DFU mode, but got error 21.

The system cannot be restored on this device. Failed to restore device in recovery mode. iBusRestore error 21 (com.apple.MobileDevice.MobileRestore – 0x15 (21))

I think they didn't try in the correct way, and are demanding Rs. 40k for a hardware issue.

Any solution to restore my Mac?

Tired recovery mode

Reinstall failed after some time and laptop went into restore mode.

Restore error at apple store

[Edited by Moderator]