In my case, I flashed a custom Xperia T kernel from a dev who modified S1_BOOT and the bad flash put my phone in the QHSUSB_DLOAD mode. I tried absolutely everything and nothing worked, the phone was completely bricked. Now, if this can happen with a bad flash from Sony, imagine the havoc cross flashing device manufacturer's causes! Samsung software on a Sony platform? It's deader than dead.