no boot in bootloader or os

Chances are Amir has solved the problem by now -- well more than a year -- but I will share my own experience, though it did not have a happy ending. My 4+ year-old ACER Iconia A210 refuses to boot, no matter which of the various reset button sequences are used. The only sequence getting a response is the combination Power, Volume -, Volume +. But rather than seeing "Booting recovery kernel image" as I should, I get:

Entering boot menu mode

 Booting failed

Bootloader vjB-3fb8d45: Starting Fastboot USB download protocol

The tablet then freezes at the ACER logo screen with the above alert in the upper left corner, and would remain so indefinitely if not powered down. There is no capability to scroll via volume buttons, choose a function via power key, or I'm guessing unlock the bootloader. I think the failure is more than a corrupted boot drive. "Entering boot menu mode" and "Starting Fastboot USB download protocol" suggest a corrupted boot BIOS, as the tablet tries to boot an image from a USB connected diagnostic device. Probably something only the factory has access to and likely tossed for this old of a model.

The simplest answer would be to swap motherboards. Given the age of Android 4.1.1 in this Iconia, I certainly realize a new tablet would be better in the long run. But I'm waiting for ACER to release its new Iconia One 10 and that can take many months. Yet at $24 minimum for a refurbished motherboard I'm leaning toward just handing this tablet over to an electronics recycler. 

I have gone to the leading Android forums to ask if any developers know of a USB tool to check my theories of a "dead and gone" tablet/motherboard. The few responses I received did not help, as all required getting the tablet to reset via button sequences, and it simply will not boot. Hence, it would seem, proving my theory.

Amir did not give enough detail to see how similar his situation is, despite a different brand. But hopefully my experience will help others with a similar issue.