My scope has fresh alk. batteries but pressing the power button has no effect.

The screen does not flash or light at all, nor does the handle-top green LED light.

It appears completely dead.

I have tried disconnect/reconnecting batteries.

I have opened it, and disconnected/reconnecting internal battery and tried again.

I have tried a USB charge cable and tried again, nothing.

Add/disconnect camera.

(No SD card.)

I have tried a mix n match of the above and nothing.

I have not tried connecting it to a PC.

HOWEVER, 

If I open it and look on the pc board, there is a micro push button switch.

If I disconnect internal battery, wait, then reconnect internal battery, then if I push and hold this button while pushing and holding the power button (with the USB power applied), the screen powers up and displays a color splash screen with model #, then seconds later goes dark.

That's the best I can get to happen, and can do it repeatedly.

If at anytime I let go of the micro-button, the screen goes dark immediately.

Once the screen comes on I can release the power button, but doing so makes no difference either way.

Can anyone explain what the problem is, what to try ?  ***

Has anyone heard of this happening before (I g0ggled-it and found nothing) ?

What is the micro button for (no best guesses please) ?