1.) Switch the unit off and remove the AC plug
2.) Hold buttons 'A' and 'B' (down next to the headphones socket)
3.) Reinsert the AC plug
The display should flash with a frequency of about 1Hz.
4.) Release the buttons
To be honest, it doesn't sound like a problem with the microprocessor, it sounds like some problem with the speaker connections. What you described sounds exactly like what would happen if the protections circuit came into operation.
Double-check that you haven't made a mistake with your speaker wiring. Make sure that your speakers aren't of too low an impedance for the 2802. I think that its specified as capable of a 6ohm load (at least that's what my 3802 does).
Hope this helps.
Andrew