[porkupan]

So, this means 'Even' Sony does not have a way to repair it yet.

Sony is a big organization. Their repairmen are not going to be trying to figure out what's wrong with every reader that comes their way - it's not worth their time and effort. They have a "repair map" - a simple algorithm they follow to analyze the problems. When they see something they haven't encountered yet, the default action is to replace the whole unit.

Of course, every hardware or firmware engineer knows that your reader is not totally dead. Its flash can be re-burned from scratch with the proper equipment, and it can be up and running in no time. It's just Sony doesn't know how it happened that your reader got into this state, and you probably didn't tell them that you f-ed it up all on your own. So they assume there is something wrong with your hardware, and they opted for the default option.

If the rootfs is not absent on the reader, but is totally dead/broken, there isn't much one can do other than reflash the reader. There may be a way to force the reader into the recovery mode (the bootloader sources seem to indicate that certain register values are examined for that purpose):

//
// check GPIO3_0 or GPIO3_30 is High
//
// return 1 if condition is true, 0 if condition is false
//
static int is_recovery_boot(void)
{
	unsigned long ulPadStatus;
	int iRet = 0;
	ulPadStatus = readl( 0x53FA4008 );
	if ( (ulPadStatus & 0x00000001) == 0 )
	{
		//mxc_uart_putstring("Jig port is Low.\n");
		iRet = 1;
	}
	else if ( ulPadStatus & 0x40000000 )
	{
		//mxc_uart_putstring("LogOut port is High.\n");
		iRet = 1;
	}
	return iRet;
}

To read the recovery update from a diagnostic card the reader must be able to boot into some valid state (requires a working rootfs with init scripts).

So, to answer your question on how brickable are the x50 readers. They can be totally killed, if you absolutely don't know what you are doing. If you follow the instructions and use verified working images the bricking is highly unlikely.