If you are running a consumer image, then there is no way to abort the player application and drop to a command line shell (bash). For this, you need to have the developer image installed.

If you have the serial port working with Hyperterminal, then at least you know your serial port dongle is working OK. The next thing to do is run the Updater program and specify the COM port that this dongle presents itself as (COM1, 2, etc.). Then point the updater at the downloaded firmware update image to perform the update. Make sure you have the correct image type for your player (Mk 1, Mk 2/2A/Riocar) and the correct sort for what you want to do (consumer, developer). Bob is your proverbial.