I foolishly reset the BIOS by accident, HELP!!!

Hi. I've replaced the trackpad button. Doing so meant having to remove the battery just to get at the thing which needed replacing. After the installation, I turned on the computer and it does that thing and go to the BIOS page whenever you remove the batter, and presents some options. I chooses to go into Bios. After applying the correct time and date, I clicked exit, AND one thing led to another and I somehow, foolishly clicked reset BIOS.

I reset the BIOS and now, I cannot boot properly without the AC. If I boot without the AC, device behaves strangely. It'll go into diagnostic boot and start prompting the user, (me) to do some tests. After I've performed those annoying tests, everything looks fine, I boot without the AC, but as soon as I touch it, or it progress into Windows setup, the laptop turns itself off. And it'll keep doing it. But, if I leave the AC in and turn it on, and the laptop turns on with out the yellow booting into diagnostic thing on the top left. Everything appears normal until I catch the DELL flicker on. It'll turn off and restart before presenting a DELL logo again before progressing onto the Windows setup screen.

I open the laptop back panel and inspect the innards to check to see if the battery is seated properly. And, it is.

I check BIOS settings, (not that I'm familiar) and everything appears to be working looking normal. Not that I'm familiar with the model. I am at a loss on how to fix it.