Hi
First of all i apologize for my bad english, but i hope that someone could understand and help me.
This is my sad experience:
I had a brandnew GP2X F-100 MK2 console with 3.0 firmware installed, so i decide to downgarde to 2.0 firmware. I followed the instructions i found on the web (using a Sandisk Sd 2Gb card and the power adaptor) but the GP2x screen showed me the massage "Firmware Upgrading" for more than two hours so i decided to turn off the console. The result was that now the Gp2x at startup shows only a perfect BLACK SCREEN!!!
Please may anyone tell me (step by step) what exactly i must or can do for unbrick my GP2x?
Was the problem the 2Gb Sandisk SD card? Which Sd card should i use?

P.S.: I tried also a Kingston 1Gb Sd card but without success. Still Black Screen

Thanks in advance for your attention.

Wait, how far do you actually get? Does nothing at all happen, or does it go black after one loading screen?

well that's why the faq says you shouldn't do it
anywayz here's a guide, i haven't bricked mine (yet) so i haven't tried it, but it makes sense.
http://www.geocities.com/joshuabissot/unbrick.html

You need to tell us EXACTLY what happens.

Ie, you turn on the power switch and what do you see? Nothing but a black screen? or does the LCD show something before going black, etc?

http://www.gp32x.com/board/index.php?showtopic=38333

When i turn on the power i see nothing but a fully black screen on the lcd.

SOLVED!!!!
I followed step by step this tutorial
http://www.oneandoneis2.com/linux/GP2X/unbrick.htm