Here's an internal email from DT (David Thomas) that describes this situatiuon and its fix
I just got a Venue master that apparently wouldn't power up for a dealer. On examining it, I found it to be intact, hardware-wise, but it had corrupted firmware, such as might happen during a botched upgrade attempt.
The wonderful thing is: THIS PROBLEM IS 100% FIELD RECOVERABLE!
It is easy to think that a unit that "won't power on" certainly isn't failing due to firmware, and even if it were, how can you upgrade if it "won't power on"? Well, actually, you can and I just did!
The way the Venue's power supply works, the micro always gets power, and it is in charge of turning the rest of the circuits on or off. If an upgrade attempt fails, it is possible that the program firmware won't work correctly, which can mean that the unit doesn't power on when the power button is pressed. Nonetheless, the micro has power.
The bootloader portion of the firmware is code protected at the factory, so that in theory, it will always be possible to recover from a botched upgrade. This case was no exception. I held down the two buttons to the left of the LCD and applied power, and the display lit up happily, displaying the word UPDATE. I was then able to load the correct firmware in from the PC, and the unit is now working!
So, word to the wise (and perhaps for the troubleshooting guide and FAQ list): a Venue that appears to have power supply problems may in fact just have bad firmware loaded. The way to check is to attempt a firmware update.