Bios mod problem

[Boguś]

Hello. I finished bios mod in my console. It was third attempt. In first attempt I installed everything normal (piggyback method on original bios), second one I wanted two programmable bios. All result was destroyed MX chip...... Third attempt was today. I install first original bios, then MX chip. Everything looks fine. I hooked up console, and it freeze on Dreamcast logo. Whats may be wrong? I think original SEGA bios is damaged. When I tried install two MX chips I overheated original one (desoldered with a heat gun). Sorry for my English. I hope you can help me.

[Gillbert]

Post some detailed/hi-res pics of your mod and we will try to help.

[Boguś]

Maybe its not hi res foto, but I dont have better way to make it. For me everything looks fine. Clear job. All legs had connection. No bridges.

https://i.imgur.com/yWLt9Xn.jpg
https://i.imgur.com/W1I6wOC.jpg

[Gillbert]

Installation seems fine to me too. Since you removed the ROM chip many times, maybe some PCB trace have gone. You'll have to check the continuity of the bios pins to the PCB traces.
Here some pics of the PCB mobo and a solder pads map.

[Boguś]

Finally I almost fixed my Dreamcast. Today I discovered bridge between legs 23 and 24 on bios. I corrected everything. Now I have second problem. After fixing bridge problem, my console start up witch few secound black logo, then dreamcast logo show up. Next after 1-2 minutes menu boots (controller working), then i see about one minute checking disc screen. After that menu works normal. Somebody know the problem?

EDIT

I make video.

https://www.youtube.com/watch?v=Uwt9gYecOJM&t
https://www.youtube.com/watch?v=JByPvgKAUAM


EDIT 2.

Now I have something else. The problem started when I desolder old bios using a heat gun, then new bios had bridge.... Maybe some balls under cpu/ gpu loose connection? I should reflow cpu/ gpu?

https://www.youtube.com/watch?v=RuV1xd3cBSE

[SWAT]

In first two videos, looks like bad connection of GD-ROM with motherboard or you damaged somethigs on this way (BIOS and GD-ROM use the same bus).
In third video, I have no idea. You have HDD/SD mods for boot DreamShell?

[Boguś]

Menu starts up normal like in third video, when I push GD-ROM. You right. I don't have HDD/SD mod. Now I give a try screw console, and change GD-Rom from other console.

EDIT

I change the GD-ROM. I see problem with G1 connector. With new GD-ROM Dreamcast works normal. Thanks for help.