After completion, the receiver will reboot itself. When you see the channel scan screen or menu, remove the USB drive.
Go to Menu → Installation → Factory Reset or Restore Defaults. Enter the PIN (usually 0000 or 1234). This clears old channel data that may conflict with the new firmware. 1509 Dvb-t2 512m Firmware Update
A: Never. The 1G firmware is for 128MB devices. Flashing it will overflow memory, causing an immediate brick. After completion, the receiver will reboot itself