As far as I can tell from the bootloader code, the Mega should flash its yellow "L" LED rapidly 3 times whenever it is reset (as the Uno does). Does yours do this when you press the reset button? Does it also do it when you attempt to upload a sketch?
No, the Mega does not flash at all when the reset button is pressed, but my Uno and Nano do.
When I try to upload a sketch, same thing, no flashing (apart from single blink on the RX led). However, it seems the Blink sketch is installed on it which flashes the 'L' LED red about once a second.
Thanks for your reply.